Metal organic framework based water capture apparatus

ABSTRACT

An apparatus for capturing a water content from a water containing gas, the apparatus comprising: a housing having an inlet into which the water containing gas can flow; a water adsorbent located in the housing, the water adsorbent comprising at least one water adsorbent metal organic framework composite capable of adsorbing a water content from the water containing gas; and a water desorption arrangement in contact with and/or surrounding the water adsorbent, the water desorption arrangement being selectively operable between (i) a deactivated state, and (ii) an activated state in which the arrangement is configured to apply heat, a reduced pressure or a combination thereof to the water adsorbent to desorb a water content from the water adsorbent.

PRIORITY CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.16/766,379, filed 22 May 2022, which is a National Stage Application ofPCT/AU2019/050860 filed 16 Aug. 2019, which claims convention priorityfrom Australian provisional patent application No. 2018903009 filed 16Aug. 2018, the contents of which should be understood to be incorporatedherein by this reference. To the extent appropriate, a claim of priorityis made to each of the above disclosed applications.

TECHNICAL FIELD

The present invention generally relates to an apparatus, a method and asystem that utilises a water adsorbent metal organic framework compositeto capture the water content of a water containing gas, such asatmospheric air. In one form, the invention is configured fortemperature swing water harvesting. In another form, the invention canbe configured for magnetic induction swing water harvesting usingMagnetic Framework Composites (MFC) —a composite material formed betweena metal organic framework and a magnetic material. However, it should beappreciated that the present invention could be used in other waterharvesting applications that utilise a water adsorbent metal organicframework composite material.

BACKGROUND OF THE INVENTION

The following discussion of the background to the invention is intendedto facilitate an understanding of the invention. However, it should beappreciated that the discussion is not an acknowledgement or admissionthat any of the material referred to was published, known or part of thecommon general knowledge as at the priority date of the application.

Water can be a scare resource in many parts of the world, particularlyin dry or arid environments. However, water vapour and droplets in theatmosphere is a natural resource that could be captured to increase theglobal supply of water.

Various atmospheric water capturing systems have been previouslydeveloped which contain an adsorbent material that can capture andrelease water, for example by heating the adsorbent material using solaror other external means.

One type of adsorption material capable of adsorbing water vapour isMetal-Organic Frameworks (MOFs). A number of MOFs are known that areable to adsorb moisture. These known MOF adsorbents physisorb water ontothe surfaces within the pores of the MOF.

Although MOFs have already been considered in numerous applications,including gas storage, separation, and dehumidification, the use of MOFsfor water capturing has only recently been proposed.

One example of MOF based water capturing is taught in Yaghi et al.“Water harvesting from air with metal-organic frameworks powered bynatural sunlight.” Science 356.6336 (2017): 430-434 (Yaghi 1), and in asubsequent publication (which provides further details of the system)Yaghi et al. “Adsorption-based atmospheric water harvesting device forarid climates.” Nature communications 9.1 (2018): 1191 (Yaghi 2). Thesystem described in both papers utilised a porous metal-organicframework (microcrystalline powder MOF-801, [Zr₆O₄(OH)₄(fumarate)₆]) tocapture water by vapour adsorption in ambient air with low RelativeHumidity (RH) (down to RH of 20% at 35° C.). The MOF-801 powder wasinfiltrated into a porous copper foam brazed on a copper substrate, tocreate an adsorbent layer with 1.79 g of activated MOF-801 with anaverage packing porosity of ˜0.85. The copper foam geometry was selectedto have a high substrate area to thickness ratio to reduce parasiticheat loss. Water was released from the MOF using a non-concentratedsolar flux below 1 sun (1 kW m⁻²), requiring no additional power inputfor producing water at ambient temperature outdoors. In Yaghi 1,condensation was driven using a condenser interfaced with athermoelectric cooler (using the cooling side of the thermoelectric“peltier” device only) to maintain the isobaric conditions of ˜1.2 kPa(20% RH at 35° C., saturation temperature of ˜10° C.) in order tocondense all of the water in the desorbed vapour. This thermoelectriccooler appears to have not been utilised in Yaghi 2. The device wasreported in Yaghi 2 to capture and deliver water at 0.25 L kg/MOF/day at20% RH and 35° C. It is noted that Yaghi 2 appears to provide correctedwater production results over those published in Yaghi 1.

Despite the promising results taught in Yaghi 1 and Yaghi 2, the use ofMOF infiltrated into a conductive substrate can still have a low energyconversion efficiency, particularly in the desorption phase using directsolar heating, thereby limiting the amount of possible water productionusing this system. For example, Yaghi 2 reports energy efficienciesreaching 60% at the gram scale. Significant thermal loss in this systemis to be expected due to the energy required to heat the thermal mass ofthe copper foam substrate.

The limitations of Yaghi 1 and Yaghi 2 demonstrate that there are stillopportunities to refine selection and further optimise the use of MOFadsorbents to capture atmospheric water. It would therefore be desirableto provide an improved or alternate water capture method and systemwhich utilises MOFs to adsorb and thus capture water from a watercontaining gas such as atmospheric air.

SUMMARY OF THE INVENTION

The present invention provides an improved and/or alternate MOF basedadsorption apparatus for capturing water from a water containing gas,such as air, for both commercial and domestic applications.

Water Harvesting Apparatus

A first aspect of the present invention provides an apparatus forcapturing a water content from a water containing gas. The apparatuscomprises:

a housing having an inlet into which the water containing gas (having awater content) can flow;

a water adsorbent enclosed within the housing (i.e. located inside thehousing), the water adsorbent comprising at least one water adsorbentmetal organic framework composite capable of adsorbing a water contentfrom the water containing gas, the metal organic framework compositecomprising: at least 50 wt % water adsorbent metal organic framework;and at least 0.1 wt % hydrophilic binder comprising a hydrophiliccellulose derivative; and

a water desorption arrangement in contact with and/or surrounding thewater adsorbent, the water desorption arrangement being selectivelyoperable between (i) a deactivated state, and (ii) an activated state inwhich the arrangement is configured to apply heat, a reduced pressure ora combination thereof to the water adsorbent to desorb a water contentfrom the water adsorbent.

The present invention provides an apparatus capable of harvesting waterfrom a water containing gas, for example ambient air, which includes aMOF based composite water adsorbent that can be used to adsorb a watercontent when the water desorption arrangement is in a deactivated stateand then selectively operated to desorb water from the water adsorbentby activating the water desorption arrangement (operating it in theactivated state). It should be understood that “selectively operable”means that a user is able to actively change the condition of the waterdesorption arrangement from between the deactivated state and activatedstate, for example switch or trigger that change of state. This activechange may be through the supply of a driving force, for exampleelectricity to power a heater, vacuum to reduce pressure or the like tothe water desorption arrangement to switch/operate the device in theactivated state. Removal of the driving force would change the waterdesorption arrangement to the deactivated state.

The apparatus is therefore configured to enable selective operation andcontrol of the adsorbing and desorbing phases of a water harvestingcycle of the water adsorbent. This selective operation advantageouslyenables the optimisation of the efficiency of water desorptionarrangement through the use of more efficient water desorptionarrangements to desorb water from the metal organic framework basedwater adsorbent compared for example to utilising solar energy. In someembodiments, this selective operation can also achieve simultaneouscondensation of the water content of any product gas flow which includesthe desorbed water entrained or otherwise contained in that flow.

The water desorption arrangement can take any number of forms dependingon whether heat and/or reduced pressure is being used to cause theadsorbed water to desorb from the water adsorbent. In some embodiments,the apparatus is designed for pressure swing adsorption, with desorptionbeing achieved by reducing the pressure for example using a vacuum pumpto evacuate the gas from around the water adsorbent. Adsorption wouldtypically be undertaken at near atmospheric pressure. In otherembodiments, temperature swing adsorption is undertaken to achieve waterharvesting. This can be achieved using direct heating methods, or insome cases using magnetic induction swing adsorption.

It should be appreciated that the capture of water from a watercontaining gas refers to separating, stripping or otherwise removing awater content from that water containing gas. The water containing gascan comprise any gas that has a water content, for example air(particularly atmospheric air), nitrogen laden with water, oxygen ladenwith water or the like.

It should also be appreciated that the water containing gas can compriseany number of gases, such as nitrogen, oxygen or the like. Inembodiments, the water containing gas comprises air, preferablyatmospheric air, more preferably ambient air. It is to be understoodthat ambient air is atmospheric air located in a particular location anda given environment. It is to be understood that the term “ambient air”is intended exclude air that has been subjected to processing forexample compressed air, degassed air (such as air degassed of watervapour), filtered air or the like. The apparatus can therefore be usedto separate and capture water content from atmospheric air and therebycapture water.

Where atmospheric air is used, the relative humidity of the atmosphericair is preferably between 25 to 100% at 22° C., preferably between 40 to100% at 22° C., more preferably between 40 to 80% at 22° C. Inembodiments, the relative humidity of the atmospheric air is between 40to 60% at 22° C., and preferably about 50% at 22° C.

The housing of the water apparatus can comprise any suitable containeror enclosure having an inlet. The housing typically also includes anoutlet through which an exit gas can flow. The exit gas typically has alower water content than the feed water containing gas, as a watercontent is adsorbed by the water adsorbent.

The apparatus may also include one or more doors or other sealingarrangements which fit over or otherwise close the inlet and any outletto enable the housing to form a closed environment (or at least a gasclosed environment), and thus enhance desorption and condensation. Anynumber of sealing doors or sealable opening arrangements may be used. Insome embodiments, the inlet and outlet include at least one fluid sealmovable from an open position to allow gas to flow through the inlet andoutlet, and a closed position where the inlet and outlet aresubstantially sealed closed to gas flow. The fluid seal can comprise atleast one movable door, preferably a least one pivotable plate or flap,more preferably at least one louver.

Temperature Swing Water Harvesting

Temperature swing adsorption water harvesting is achieved in someembodiments using direct conductive heat transfer between a heat sourceand the water adsorbent. In these embodiments the water desorptionarrangement includes at least one heat transfer arrangement in directthermal conductive contact with the water adsorbent. The heat transferarrangement is also preferably in thermal conductive contact with aheating device. The heat transfer arrangement typically includes one ormore heat transfer elements that provide conductive heat transfer fromthe heating device to the water adsorbent. In some embodiments, the heattransfer arrangement includes at least one heat transfer element thatextends from the heating device to the water adsorbent. That heattransfer element may comprise at least one elongate rod, pipe, rib orfin.

A number of suitable heating devices are available. In exemplaryembodiments, the heating device comprises at least one peltier device.It should be appreciated that a peltier device is also known as apeltier heat pump, solid state refrigerator, thermoelectric heat pump,thermoelectric heater or thermoelectric cooler. The presentspecification will use the term “peltier device” to describe thiselement of the apparatus. However, it should be understood that each ofthese alternative terms could be equally used interchangeably todescribe this element of the apparatus.

The peltier device is generally selected to be suitable to providesufficient energy to desorb water from the shaped water adsorbentcomposite bodies. The peltier device is therefore selected to have amaximal heat flow of at least 50 W, preferably at least 75 W, morepreferably at least 100 W, and yet more preferably at least 110 W. Thepeltier device is preferably selected to be able to heat the packed bedto at least 50° C., preferably at least 60° C., more preferably to atleast 65° C., and yet more preferably to at least 70° C. In someembodiments, peltier device is selected to be able to heat the packedbed to between 50 and 90° C., preferably between 50 and 80° C., and morepreferably between 60 and 80° C. In some embodiments, peltier device isselected to be able to heat the packed bed to between 65 and 85° C.,preferably between 70 and 80° C., and more preferably around 75° C.

The apparatus can also further comprise at least one heat transferarrangement in thermal communication with the peltier device in order tobest utilise the heated side of the peltier device. The water adsorbentis located in contact with the heat transfer arrangement, for examplebeing housed within or coated on at least part or the heat transferarrangement.

The heat transfer arrangement can have any number of forms, including avariety of heat exchanger configurations. In a number of embodiments theheat transfer arrangement comprises a heat sink (i.e. a conductive heattransfer arrangement), preferably a heat sink having a plate or finarrangement. In some embodiments, the heat sink arrangement comprises aplurality of spaced apart heat transfer elements. The heat transferelements typically comprise a planar support element, preferablyselected from at least one of plates or fins

The shaped water adsorbent composite bodies can be located around,within or in any number of other configurations in contact with the heattransfer arrangement. In preferred embodiments, the shaped wateradsorbent composite bodies are located within the heat transferarrangement. In this arrangement, the water adsorbent is housed orfitted as a packed bed between at least two heat transfer elements. Thewater adsorbent is packed into at least some, preferably all of the freevolume of the heat transfer arrangement.

Adsorption and desorption from the shaped water adsorbent compositebodies can be enhanced by driving fluid flow through and over the wateradsorbent. In some embodiments, the apparatus further includes at leastone fluid displacement device to drive fluid flow through the packedbed. The fluid displacement device preferably comprises at least onefan. Flow can be driven through the packed bed at a number of flowrates. In order to optimise water adsorption and desorption, the fluiddisplacement device preferably creates a fluid flow of at least 3 m³/hr,preferably 3 to 300 m³/hr, and more preferably 3 m³/hr to 150 m³/hrthrough the packed bed. It should be appreciated that the amount of airrequired to flow through the packed bed depends on the moisture level inthe water containing gas and the efficacy of capture.

The apparatus may also include a condenser system for cooling theproduct gas flow from the water adsorbent. In some embodiments, thecondenser system comprises a cooling device, preferably a cooling trap.In the embodiments that include a peltier device, the peltier device canalso form part of the condenser system. Here each peltier device has ahot side and a cold side, with the hot side of each peltier device beingin thermal communication with at least one heat sink, and the cold sideof each peltier device forming part of the condenser system.

The cold side of each peltier device can also be in thermalcommunication with at least one heat transfer arrangement, preferably atleast one heat sink in embodiments. The heat transfer arrangementprovides further surface area to contact the product gas flow to assistcondensation of the water content therein.

Metal Organic Framework Composite

The metal organic framework composite can be provided in the apparatusin any suitable form. The inventors envisage that this may be in anynumber of formulations and forms including shaped bodies (for examplepellets or extrusions), coatings, plates, sheets, strips or the like.

The water adsorbent is a metal organic framework composite comprising:

at least 50 wt % water adsorbent metal organic framework; and

at least 0.1 wt % hydrophilic binder.

That metal organic framework composite may take various forms dependingon the desired application, apparatus configuration and adsorptionrequirements. For example, the metal organic framework composite maycomprises a coating applied to the surface of the water desorptionarrangement. In other embodiments, the metal organic framework compositecomprises shaped water adsorbent composite body.

In one particular form, the metal organic framework composite comprisesshaped water adsorbent composite body having at least one mean dimensionof greater than 0.5 mm. This shaped water adsorbent composite body isformed from a mixture of a water adsorbent metal organic framework and ahydrophilic binder that is preferably optimised for use in a packed bedadsorption system. The combination of the water absorbent metal organicframework and hydrophilic binder have a surprising synergistic effect,facilitating greater water adsorption compared to the use of other typesof binders, for example hydrophobic binders.

For atmospheric water harvesting/capture applications, the inventorshave found that three-dimensional shaped bodies with the definedcomposition have excellent water adsorption properties, and suitablewater adsorption kinetics, even at low H₂O partial pressures. Theinventive shaped water adsorbent composite body also has usefulbreakthrough test properties for water capture from a water containinggas (water vapour capture), and has been found to have suitablestability when consolidated, shaped and heated.

Ideally, the shaped water adsorbent composite body should have a goodenough affinity for water to adsorb the water, but not have too highaffinity for water that excessive energy needs to be expended to desorbwater therefrom. Preferably, the heat of adsorption for water andadsorbent range from 10 to 100 kJ/mol MOF for water adsorbed in and/oron the shaped water adsorbent composite body.

Optimising the composition of a shaped water adsorbent composite bodyinvolves a number considerations, including:

-   1. Water stability—the components, and in particular the MOF should    be water stable.-   2. Adsorption reproducibility, the shaped water adsorbent composite    body should retain adsorption capacity after multiple    adsorption/desorption cycles, preferably at least 10 cycles, more    preferably at least 100 cycles.-   3. Ease of production, the shaped water adsorbent composite body and    components thereof should be easy to produce from readily available    precursor materials.-   4. High water uptake from air even at low humidity values.-   5. A good affinity for water. The MOF component of the composite    body should have a good enough affinity for water to enable the MOF    to adsorb the water, but not have too high affinity for water that    excessive energy needs to be expended to desorb water therefrom.    Here the thermodynamics of water adsorption and desorption need    consideration to ensure the MOF does not require excessive energy    (kJ/mol MOF) to desorb water therefrom, and thereby adversely affect    the energy efficiency of the system.

The MOF and other component materials must also meet food for humanconsumption regulations in relevant countries where the shaped wateradsorbent composite body is required for water production for humanconsumption.

The shaped water adsorbent composite body preferably has a highadsorption of water from a water containing gas such as air even at lowhumility levels. In embodiments, the shaped water adsorbent compositebody is able to adsorb a water content from a water containing gas,preferably air, having a humidity of greater than 20% at 20° C.,preferably from 20 to 100% at 20° C., preferably from 20 to 80% at 20°C., and more preferably from 25 to 60% at 22° C. In embodiments, thehumidity of the water containing gas is between 25 to 100% at 22° C.,preferably between 40 to 100% at 22° C., preferably between 40 to 80% at22° C., preferably between 40 to 60% at 22° C., and more preferablyabout 50% at 22° C. In embodiments, the humidity of the water containinggas is between 20 to 100% at 35° C., preferably between 20 to 80% at 35°C., preferably between 20 to 60% at 35° C., and more preferably about30% at 22° C.

The shaped water adsorbent composite body preferably has an averagesurface area of at least 700 m²/g, and preferably greater than 800 m²/g.

The shaped water adsorbent composite body is preferably configured withdimensions that are suitable for use in a packed bed adsorption system,in which a plurality of the shaped bodies are packed at a high packingdensity 0.10 to 1.0 kg/L, preferably 0.25 to 0.5 kg/L, more preferablybetween 0.25 and 0.35 kg/L, and yet more preferably about 0.29 kg/Lbetween two support surfaces. The dimensions of the shaped wateradsorbent composite body can be optimised to suit this application. Foruse in a packed bed, the shaped water adsorbent composite body has atleast one mean dimension of greater than 0.5 mm. This ensures that theadsorbent composite body has sufficient size to allow gas flow around.For example, fine powder (e.g. having an average particle size of lessthan 10 micron) typically provides too dense a particle packing for usein a packed bed adsorption system. In some embodiments, the shaped wateradsorbent composite body has at least one mean dimension of greater than0.8 mm, preferably at least 1 mm, preferably at least 1.2 mm, and yetmore preferably at least 1.5 mm. In embodiments, each of the mean width,mean depth and mean height of the shaped water adsorbent composite bodyare greater than 0.5 mm, and preferably greater than 1 mm.

It should be appreciated that “mean dimension” refers to the mean(average) dimension of at least one of the width, depth or height of theshaped water adsorbent composite body. Accordingly, at least one of themean width, mean depth or mean height must be greater than the specifieddimensional value.

The shaped water adsorbent composite body can have any suitablegeometry. The shape of the composite bodies has an impact on thepressure drop of local fluid flow (in the vicinity of the bodies), andtherefore, the performance of any packed bed adsorption system. Forexample, the shaped water adsorbent composite body could comprisepellets (for example, disk-shaped pellets), pills, spheres, granules,extrudates (for example rod extrudates), honeycombs, meshes or hollowbodies. In embodiments, the shaped water adsorbent composite body isformed as a three dimensional body, preferably three dimensionallyshaped. In particular embodiments, the shaped water adsorbent compositebody comprises an elongate body having a circular or regular polygonalcross-sectional shape. For example, the shaped water adsorbent compositebody may have a square or triangular cross-sectional shape. In anexemplary form, the shaped water adsorbent composite body comprises anelongate body having a triangular cross-sectional shape, preferablyequilateral triangle cross-sectional shape. In one form, the shapedwater adsorbent composite body has equilateral triangle cross-section,preferably the sides of the equilateral triangle are at least 1 mm inlength, preferably between 1.0 and 1.5 mm in length. The elongate shapedwater adsorbent composite body is preferably from 1 to 5 mm in length(longitudinal length), more preferably 1 to 4 mm in length.

Metal-Organic Frameworks

Metal-organic frameworks (MOFs) comprise the major adsorbent constituentof the shaped water adsorbent composite body. MOFs are a crystallinenanoadsorbent with exceptional porosity. MOFs consist of metal atoms orclusters linked periodically by organic molecules to establish an arraywhere each atom forms part of an internal surface. MOFs as aphysisorbent achieve strong adsorption characteristics through theinternal surfaces of the MOF porous structure. The strength of thisinteraction depends on the makeup of the adsorbent surface of the MOF tocapture H₂O molecules. Advantageously, the surface chemistry andstructure of MOFs can be tuned for a specific application, whereperformance criteria such as adsorption/desorption rate, capacity as afunction of pressure, and operating temperature may be of particularimportance.

The shaped water adsorbent composite body utilises the selectivity ofthe MOF to adsorb water rather than other components in the air, such asoxygen and nitrogen. That is, capturing of water from a water containinggas (such as air) using a MOF adsorbent. For this functionality, theshaped water adsorbent composite body comprises at least 50 wt % wateradsorbent MOF, preferably at least 70 wt % water adsorbent MOF, morepreferably at least 80 wt % water adsorbent MOF, yet more preferably atleast 85 wt % water adsorbent MOF and yet more preferably at least 90 wt% water adsorbent MOF.

It should be appreciated that “water adsorbent metal organic framework”means a water stable metal organic framework that has a good affinityfor water, adsorbing water even at low humidity values. Preferably, theheat of adsorption for water ranges from 10 to 100 kJ/mol MOF for wateradsorbed on the MOF. Ideally, a water adsorbent MOF should have a goodenough affinity for water to enable the MOF to adsorb the water, but nothave too high affinity for water that excessive energy needs to beexpended to desorb water therefrom. Here the thermodynamics of wateradsorption and desorption need consideration to ensure the MOF does notrequire excessive energy (kJ/mol MOF) to desorb water therefrom, andthereby adversely affect the energy efficiency of the system.

Any suitable water adsorbent metal organic framework can be used. Insome embodiments, the water adsorbent metal organic framework comprisesat least one of aluminium fumarate (AlFu), MOF-801, MOF-841, M₂Cl₂BTDDincluding Co₂Cl₂BTDD, Cr-soc-MOF-1, MIL-101(Cr), CAU-10, alkali metal(Li⁺, Na⁺) doped MIL-101(Cr), MOF-303 (Al), MOF-573, MOF-802, MOF-805,MOF-806, MOF-808, MOF-812, or mixtures thereof. In embodiments, thewater adsorbent metal organic frameworks are preferably selected fromaluminium fumarate, MOF-303, MOF-801, MOF-841, M₂Cl₂BTDD, Cr-soc-MOF-1,or MIL-101(Cr).

In particular embodiments, the water adsorbent metal organic frameworkincludes a plurality of multidentate ligands of which at least oneligand is from selected from fumarate (fumaric acid) or3,5-pyrazoledicarboxylic add (H₃PDC) based ligands. In some embodiment,the metal ion is selected from Fe³⁺, Li⁺, Na⁺, Ca²⁺, Zn²⁺, Zr⁴⁺, Al³⁺,K⁺, Mg²⁺, Ti⁴⁺, Cu²⁺, Mn²⁺ to Mn⁷⁺, Ag⁺, or a combination thereof. Inpreferred embodiments, the metal ion is selected from Zr⁴, Al³⁺ orcombinations thereof. Examples include MOF-303, [Al(OH)(C₅H₂O₄N₂)(H₂O)]and MOF-573 [Al(OH)(C₅H₂O₄N₂)(H₂O)] constructed by linking aluminium(III) ions and 3,5-pyrazoledicarboxylic add and AlFu.

In particular embodiments, the water adsorbent metal organic frameworkcomprises a porous aluminium-based metal-organic framework (MOF)comprising inorganic aluminium chains linked via carboxylate groups of1H-pyrazole-3,5-dicarboxylate (HPDC) linkers, and of formula:[Al(OH)(C₅H₂O₄N₂)(H₂O)], wherein: each Al (III) ion is capped by four Oatoms from four different carboxylate groups and two O atoms from twohydroxyl groups forming AlO₆ octahedra, and the AlO₆ octahedra formcorner-sharing chains, depending on the cis- and trans-position of thetwo adjacent bridging hydroxyl groups, helical chains in MOF-303 (cis-)and MOF-573 (trans-) form respectively.

In embodiments, the MOF is MOF-303, wherein: the linkers further bridgetwo of the chains together, leading to the formation of a 3D frameworkdelimiting square-shaped one dimensional channels with diameter of 6 Åin diameter (measured by the largest fitting sphere); the MOF-303 has atopology of xhh; and/or the MOF has permanent porosity and aBrunauer-Emmett-Teller (BET) surface area of 1380 and pore volume of0.55 cm³ g⁻¹.

In embodiments, the MOF is MOF-573, wherein: the linkers further bridgetwo of the chains together, leading to the formation of a 3D frameworkdelimiting square-shaped one dimensional channels with diameter of 5 Åin diameter (measured by the largest fitting sphere); the MOF has atopology of upt; and/or the MOF has permanent porosity and aBrunauer-Emmett-Teller (BET) surface area of 980 m² g⁻¹ and pore volumeof 0.56 cm³ g⁻¹.

Water production for human consumption requires the use of materialsthat meet food for human consumption regulations in the relevantcountries. Therefore in an exemplary embodiment, the water adsorbent MOFcomprises aluminium fumarate (AlFu) MOF. Applicant notes that theadvantage of using AlFu is that it is the MOF is cheap and easy to make.

The water adsorbent metal organic framework should preferably embody anumber of properties to maximise the functionality of the shaped wateradsorbent composite body. For example, the water adsorbent metal organicframework preferably has an average surface area of at least 700 m²/g,and preferably greater than 800 m²/g. The water adsorbent metal organicframework also preferably has a pore size of at least 2 nm, preferablygreater than 5 nm. The pore size should be sufficient to at least fit awater molecule therein.

In the present invention, the water adsorbent MOF is provided as apulverulent material preferably a powder or particulates. Inembodiments, the water adsorbent metal organic framework has a particlesize of less than 800 μm, preferably less than 600 μm, and morepreferably less than 500 μm. In particular embodiments, the wateradsorbent MOF powder has a particle size of less than 500 μm, preferablyless than 300 μm, more preferably less than 212 μm, yet more preferablyless than 150 μm, and in some embodiments less than 88 μm. It should beappreciated that particle size is typically measured in terms of meshsize through which the particles are sieved. Therefore in embodiments,the water adsorbent MOF powder has a particle size of less than 60 mesh(250 μm), preferably less than 100 mesh (149 μm), preferably less than140 mesh (105 μm), and more preferably less than 170 mesh (88 μm). Thewater adsorbent MOF powder preferably also has a mean particle size ofbetween 10 and 100 μm, more preferably between 20 and 80 μm. In otherembodiments, the water adsorbent MOF powder has a mean particle size ofbetween 10 and 80 μm, and preferably between 20 and 60 μm.

Hydrophilic Binder

A water adsorbent MOF powder mixture is not ideal if used in a packedbed adsorption system. Powder alone packs too densely and therefore hastoo great of pressure drop across the adsorption unit. Therefore powderalone cannot be used. The inventors have found that the water adsorbentMOF should be shaped prior to packing into a packed bed water adsorbentsystem to form a shaped water adsorbent composite body, for example apellet, for use in a packed bed adsorption system.

The shaping process is facilitated through the use of a binder. Whilstit may be possible to form a shaped composite body without the use of abinder, shaped composite bodies that include binders in theircomposition tend to have greater structural strength and stability whenused in a packed bed water adsorbent system. A shaped composite bodysuch as a pellet therefore facilitates continuous operation of a packedbed adsorption system.

The inventors have surprisingly found that a hydrophilic binder must beused to impart optimal water adsorption properties to the shaped wateradsorbent composite bodies. The inventors have found thatnon-hydrophilic binders, in particular hydrophobic binders (for examplecellulose siloxane), deliriously affect the water adsorption propertiesof the shaped water adsorbent composite bodies. The use of a hydrophilicbinder is therefore important for optimal moisture capture properties ofthe packed bed water adsorption system.

A variety of hydrophilic cellulose derivative binders may be used in theshaped water adsorption body. The hydrophilic binder can be organic orinorganic, and should not block the pores of the water adsorbent MOF.The hydrophilic binder comprises a hydrophilic cellulose derivative,preferably alkyl cellulose, hydroxyalkyl cellulose, or carboxyalkylcellulose derivatives. Particularly suitable hydrophilic binders can beselected from at least one of hydroxypropyl cellulose (HPC),hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropylmethyl cellulose (HPMC), ethyl hydroxyethyl cellulose, methyl cellulose,carboxymethyl cellulose (CMC). However, it should be appreciated thatother binders are also possible. In preferred embodiments thehydrophilic binder comprises hydroxypropyl cellulose (HPC). It should beappreciated that the additives depend on the application in which theshaped bodies are being used. Where water is being produced for humanconsumption the binder(s) preferably comprise an approved excipient forhuman consumption. Examples of approved excipients for human consumptioninclude approved excipients for food or pharmaceuticals. Approved foodgrade or pharmaceutical grade binders are preferred.

The shaped water adsorbent composite body includes at least 0.1 wt %hydrophilic binder, and preferably at least 0.2 wt % hydrophilic binder.In embodiments, the shaped water adsorbent composite body includesbetween 0.2 and 5 wt % hydrophilic binder. In some embodiments, theshaped water adsorbent composite body can comprise between 0.5 and 3 wt% hydrophilic binder, more preferably between 0.8 and 2 wt % hydrophilicbinder, and yet more preferably about 1 wt % hydrophilic binder. Itshould be appreciated that the amount of binder is selected based on theproperties and particle size (mean size and particle distribution) ofthe water adsorbent MOF.

Lubricants

The shaped water adsorbent composite body preferably comprises less than0.5 wt % lubricant, preferably less than 0.1 wt % lubricant. Suitablelubricants include surfactants and their salts. Examples of suitablelubricants include magnesium stearate, aluminium oxide, sodium oleate,glycerides, di-glycerides, tri-glycerides, fatty acids, oils includingsilicon oils and mineral oils and mixtures thereof. It should beappreciated that the additives depend on the application in which theshaped bodies are being used. Where water is being captured and producedfor human consumption the lubricants preferably comprise an approvedexcipient for human consumption. Examples of approved excipients forhuman consumption include approved excipients for food orpharmaceuticals. Approved food grade or pharmaceutical grade lubricantsare preferred. As discussed below, one or more lubricant is added to themixture to assist with shaping and forming processes when making theshaped water adsorbent composite body.

Packed Bed Adsorption Apparatus

In some embodiments, the apparatus comprises a packed bed adsorptionsystem that includes shaped composite MOF bodies as discussed above. Insuch embodiments, the water adsorbent is a metal organic frameworkcomposite comprising: at least 50 wt % water adsorbent metal organicframework; and at least 0.1 wt % hydrophilic binder and has at least onemean dimension of greater than 0.5 mm. In this aspect, the shaped bodiesare collected in a packed bed that is enclosed in the housing. Thehousing is preferably a fluid tight housing.

The housing preferably includes two spaced apart support membranesconfigured to allow gas flow therethrough each membrane. The pluralityof said shaped water adsorbent composite bodies form a packed bedtherebetween and being compressed therebetween. In embodiments, theshaped water adsorbent composite bodies are packed at a density from0.10 to 1.0 kg/L, preferably 0.25 to 0.5 kg/L, and more preferablybetween 0.25 and 0.35 kg/L. In some embodiments, the shaped wateradsorbent composite bodies are packed at a density of about 0.25 kg/L.In other embodiments, the shaped water adsorbent composite bodies arepacked at a density of about 0.29 kg/L. As with any packed bed, it isimportant that the adsorbent is packed tightly and substantiallyuniformly throughout the packed bed volume to avoid short circuiting ofany adsorbent in that packed bed. Any flow that is able to avoid orfollow a shorter/short circuit route through the packed bed will avoidhaving water removed from that stream. Short circuit flow wouldadversely affect the energy efficiency and water production rate of thesystem. Tight and uniform packing also ensures uniform path lengths tooptimise adsorption performance.

The apparatus may use a low or reduced pressure (sometimes referred toas a vacuum environment) to direct the released water to the condenser.In embodiments, the pressure is less than 100 mbar, preferably less than50 mbar, more preferably less than 35 mbar. In other embodiments, thepressure is less than 500 mbar. In other embodiments, the released wateris entrained in a gas flow, for example a flow of the water containinggas or another gas such as an inert or other dry gas, and directed tothe condenser.

The flow rate of the water containing gas can also be varied to optimisethe water adsorption of the packed bed of shaped water adsorbentcomposite bodies. In embodiments, the water containing gas is fedthrough the packed bed of shaped water adsorbent composite bodies at asfast a flow rate that is possible for the apparatus whilst the wateradsorbent MOF is still adsorbing water from the water containing gas. Itshould be appreciated that the particular flow rate is dependent on thewater content of the water containing gas, as this determines the massof water a particular volume of gas will contain. The water content ofthe water containing gas is dependent on the relative humidity of thatcontaining gas as well as the temperature and pressure. Where theapparatus is fed ambient air, a higher flowrate will be required forlower humidity air as compared to higher humidity air at the sametemperature to maintain a desired cycle time.

The source of humid air used can be a very low relative humidity,mimicking the humidity levels found on the driest places on Earth. Inembodiments, the humidity of the air is greater than 20% at 20° C.,preferably from 20 to 100% at 20° C., preferably from 20 to 80% at 20°C., and more preferably from 25 to 60% at 22° C. In embodiments, thehumidity of the air is between 40 to 100% at 22° C., preferably between40 to 100% at 22° C., preferably between 40 to 80% at 22° C., preferablybetween 40 to 60% at 22° C., and more preferably about 50% at 22° C. Inembodiments, the humidity of the air is between 20 to 100% at 35° C.,preferably between 20 to 80% at 35° C., preferably between 20 to 60% at35° C., and more preferably about 30% at 22° C.

The packed bed adsorption system can be configured for magneticinduction swing water harvesting (adsorption-desorption cycling). Here,the water adsorbent is a Magnetic Framework Composite comprising amixture of at least 50 wt % water adsorbent metal organic framework andfrom 0.2 to 10 wt % magnetic particles having a mean particle diameterof less than 200 nm, and the water desorption arrangement comprises analternating current (AC) magnetic field generator located within and/oraround the water adsorbent configured to apply an AC magnetic field tothe water adsorbent. The water adsorbent preferably comprises shapedwater adsorbent composite bodies located in a packed bed in the housing.The shaped water adsorbent composite bodies are preferably packed at adensity from 0.10 to 1.0 kg/L, preferably 0.25 to 0.5 kg/L, and morepreferably between 0.25 and 0.35 kg/L.

The AC magnetic field generator preferably comprises at least oneinduction coil located within and/or around the packed bed of shapedwater adsorbent composite bodies. The alternating current magnetic fieldgenerator is designed to irradiate the packed bed of shaped wateradsorbent composite bodies with an AC magnetic field to release adsorbedwater from the packed bed of shaped water adsorbent composite bodieswhen activated.

Magnetic Particles

Where inductive heat generation is desired to use for water desorption,the shaped water adsorbent composite body may include magneticparticles. In these embodiments the shaped water adsorbent compositebody contains from 0.2 to 10 wt % magnetic particles having a meanparticle diameter of less than 200 nm. In some embodiments, the shapedwater adsorbent composite body may comprises between 0.5 and 7 wt %magnetic particles, and in some embodiments between 1 to 5 wt % magneticparticles.

The use of this composite material combines the exceptional adsorptionperformance of MOFs and enables the use of high efficiency of magneticinduction heating to desorb water from the MOF. The shaped wateradsorbent composite body is formed of a magnetic framework composite(MFCs), a composite material which combines magnetic particles with MOFcrystals. The incorporation of magnetic particles (typically micro- ornano-sized magnetic particles) with MOFs allows the generation of heaton exposure to an alternating current (AC) magnetic field. MFCs cantherefore be regenerated using an AC magnetic field, as a result ofgenerating heat within the composite material, and which in returnreleases the adsorbed fluid from the pores of the MOF part of the MFC.

This process uses the heat generated as a result of static hysteresisand dynamic core losses of ferro/ferrimagnetic particles induced by anexternal AC magnetic field. The generation of heat via induction heatingoccurs remotely, and resultant heat is targeted, making the heatingprocess isolated and thus energy efficient.

The magnetic properties of the magnetic framework composites areprovided by the magnetic particles mixed within the composite. Asoutlined above, the magnetic particles can be utilised to generate heaton exposure to an alternating current (AC) magnetic field, and therebycan be used to conduct magnetic induction swing adsorption process forwater adsorbed on the water adsorbent MOF.

The amount of magnetic particles is selected to provide a desired heatgeneration profile and magnitude on the application an AC magneticfield. Typically, the amount of magnetic particles in the shaped wateradsorbent composite body is between 0.2 and 10 wt %. In embodiments, theshaped water adsorbent composite body may comprise between 0.5 and 7 wt% magnetic particles, and preferably between 1 to 5 wt % magneticparticles.

A wide variety of magnetic particles can be used in the inventive shapedadsorption body. In embodiments, the magnetic particles compriseferromagnetic, paramagnetic, or superparamagnetic particles. Inembodiments, the magnetic particles comprise metal chalcogenides.Suitable metal chalcogenides comprise magnetic particles comprising anycombination of element or ionic form thereof of M selected from at leastone of Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta,Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn,Cd, Hg, B, Al, Ga, In, TI, Si, Ge, Sn, Pb, As, Sb, Bi, or theircombinations, in combination with elements or elemental form of at leastone of O, S, Se, or Te. In some embodiments, the metal chalcogenide havethe formula M_(x)N_(y)C_(z), where M and N are selected from at leastone of Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta,Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn,Cd, Hg, B, Al, Ga, In, TI, Si, Ge, Sn, Pb, As, Sb, Bi, C is selectedfrom at least one of O, S, Se, Te, x is any number from 0 to 10, y isany number from 0 to 10 and z is any number from 0 to 10. The metalchalcogenide particles may in some embodiments have a core-shellstructure in which the core comprises at least one metal chalcogenide aspreviously described and the shell comprises at least one metalchalcogenide as previously described. In some forms, the core-shellstructure may include multiple shells. In embodiments, the magneticparticles comprise at least one of MgFe₂O₄, Fe₃O₄, CoFe₂O₄, NiFe₂O₄,Pyridine-2,6-diamine-functionalized SiO₂,Pyridine-2,6-diamine-functionalized Fe₃O₄, or C-coated Co.

The magnetic particles can comprise any number of shapes andconfigurations. In embodiments, the magnetic particles compriseparticles having irregular shapes. In some embodiments, the magneticparticles comprise particles having regular three-dimensional shapes,for example spherical, platelet, rod, cylindrical, ovoidal or the like.In some embodiments, the magnetic particles comprise a plurality ofmagnetic nanospheres. The size of the magnetic particles is typicallyselected for the desired packed bed application and configuration.Generally, the magnetic particles comprise nano- or micro-particles. Themagnetic particles have a mean particle diameter of less than 200 nm,preferably less than 150 nm, more preferably between 1 to 100 nm. Insome embodiments the magnetic particles have a mean particle diameter ofless than 50 nm. In some embodiments the magnetic particles have a meanparticle diameter of between 1 and 200 nm, preferably between 5 and 100nm, more preferably between 5 to 30 nm, and yet more preferably between5 to 30 nm. In some embodiments, the magnetic particles have a meanparticle diameter of around 20 nm. It is noted that the magneticparticles need to be large enough to not foul the pores of the wateradsorbent MOF.

The combination of the magnetic particles with MOFs to form a magneticframework composite material yields an adsorbent with exceptionaladsorption behaviour as a result of the MOFs and high efficiency ofinduction heating as a result of the magnetic particles.

Method of Capturing Water Content from a Water Containing Gas

A second aspect of the present invention provides a method of capturinga water content from a water containing gas, comprising at least onecycle of:

feeding a water containing gas through the inlet of a housing and over awater adsorbent enclosed within the housing such that the wateradsorbent adsorbs water from the water containing gas, the wateradsorbent comprising at least one water adsorbent metal organicframework composite capable of adsorbing a water content from the watercontaining gas such that the water adsorbent adsorbs water from thewater containing gas, the metal organic framework composite comprising:at least 50 wt % water adsorbent metal organic framework; and at least0.1 wt % hydrophilic binder comprising a hydrophilic cellulosederivative,

operating at least one water desorption arrangement to change from aninactive state to an activated state to apply heat, a reduced pressureor a combination thereof to the water adsorbent so to release at least aportion of the adsorbed water therefrom into a product fluid flow, and

directing the product fluid flow to a condenser system to separate awater content from the product fluid flow,

wherein the water desorption arrangement is in contact with and/orsurrounding the water adsorbent.

The second aspect of the present invention also provides a method ofcapturing a water content from a water containing gas using theapparatus according to the first aspect of the present invention. Themethod comprises at least one cycle of:

feeding a water containing gas through the inlet of the housing and overthe water adsorbent such that the water adsorbent adsorbs water from thewater containing gas, the water desorption arrangement being in thedeactivated stated;

operating the at least one water desorption arrangement in the activatedstate to apply heat, a reduced pressure or a combination thereof to thewater adsorbent so to release at least a portion of the adsorbed watertherefrom into a product fluid flow; and

directing the product fluid flow to a condenser system to separate awater content from the product fluid flow.

In this aspect of the present invention a moisturized gas stream is fedover the water adsorbent. After the absorbent is charged with watervapour, the water desorption arrangement is activated to heat, a reducedpressure or a combination. Consequently, the water adsorbent is drivento release at least part of the adsorbed water content. The desorbedwater can be condensed in a condenser system, for example in a coldtrap.

It should be appreciated that the apparatus and features thereof used inthe method of this second aspect of the present invention can alsoinclude the features previously taught in relation to the first aspect.

The method preferably further comprises the step of: closing the inletand outlet of the housing prior to operating the at least one waterdesorption arrangement. This creates a closed gas sealed environment inthe housing allowing capture of the water content therein. The relativehumidity inside the housing increases to high values, and watercondenses in the condenser system for collection.

It is to be understood that this method is a cyclical method, where thesteps of adsorbing water in the water adsorbent, releasing that adsorbedwater through operation of the water desorption arrangement andcondensing that water is conducted in a repetitive cycle so tocontinuously produce water. The cycle time typically depends onconfiguration of the water adsorbent and the adsorption system, theamount of water adsorbent MOF, breakthrough point, saturation point,temperature, pressure and other process conditions. In some embodiments,one cycle of the method has a duration of less than 10 hours, preferablyless than 8 hours, more preferably less than 7 hours, and morepreferably 6 hours or less. In other embodiments, the cycle time of thismethod steps are approximately 30 minutes in duration. However, othercycle times between 10 minutes to 10 hours could be possible dependingon the configuration of the apparatus.

As noted above, the apparatus of the present invention can be configuredfor temperature swing water harvesting (adsorption-desorption cycling).In these systems, a heat source is required to heat the packed bed ofshaped water adsorbent composite bodies. In some embodiments, operatingthe at least one water desorption arrangement comprises operating atleast one peltier device to heat water adsorbent so to release at leasta portion of the adsorbed water therefrom into the product fluid flow.The at least one peltier device may also form part of the condensersystem configured to cool the product fluid flow. This arrangementadvantageously utilises both the heated and cooled side of the usedpeltier device or devices.

In other embodiments the apparatus of the present invention can beconfigured for magnetic induction swing water harvesting. Here, the stepof operating the at least one water desorption arrangement comprisesapplying an alternating current magnetic field to a packed bed of shapedwater adsorbent composite bodies, thereby generating heat within theshaped water adsorbent composite bodies, so to release at least aportion of the adsorbed water therefrom into a product fluid flow, theshaped water adsorbent composite comprises at least 50 wt % wateradsorbent metal organic framework; and at least 0.1 wt % hydrophilicbinder and from 0.2 to 10 wt % magnetic particles having a mean particlediameter of less than 200 nm.

The shaped water adsorbent composite bodies in this method undergomagnetic induction vacuum swing adsorption to capture water from thewater containing gas fed into the packed bed of shaped water adsorbentcomposite bodies. Application of the AC magnetic field depends on theamount of moisture adsorbed in the shaped water adsorbent compositebodies in the packed bed. This method therefore takes advantage of thehigh energy conversion efficiency of magnetic induction heating. Inembodiments, the apparatus and method has an energy conversionefficiency of greater than 90%, preferably greater than 95% and in someembodiments up to 98% was achieved. Furthermore, the use of rapidheating through magnetic induction heating enables short cycle times tobe achieved. In embodiments, the method has a cycle time of less than 2hours, preferably less than 1 hour.

Adsorption is a transient process. The amount of material adsorbedwithin a bed depends both on position and time. The active adsorptionregion of a packed bed shifts away from the inlet and through the bed astime goes on. This mass transfer zone moves through the bed until it“breaks through”. The fluid emerging from the bed will have little or nosolute remaining—at least until the bulk of the bed becomes saturated.The breakthrough point occurs when the concentration of the fluidleaving the bed spikes as unadsorbed solute begins to emerge. The bedstill adsorbs water, though at a slower rate than before thebreakthrough point until the bed becomes saturated, and no further watercan be adsorbed, defined as the “saturation point” of the bed.Therefore, in terms of the saturation point of the packed bed, thealternating current magnetic field is preferably applied when the packedbed has adsorbed water equivalent to at least 75% of the saturationpoint, preferably at least 80%, more preferably at least 90% of thesaturation point of the packed bed. This ensures that the adsorptioncapacity of the packed bed is substantially utilised, but allows thewater to be released before the packed bed is fully saturated.

The AC magnetic field is applied for a length of time required tosubstantially release the water adsorbed on the shaped water adsorbentcomposite bodies in of the packed bed. That application time depends onthe shape, size and configuration of the packed bed, shape, size andconfiguration of the AC magnetic field generator, the applied magneticfield strength and the amount of magnetic particles in the shaped wateradsorbent composite bodies. In some embodiments, the AC magnetic fieldis applied for at least 1 second. In embodiments, the AC magnetic fieldis applied for between 1 and 120 seconds, preferably between 1 and 60seconds, more preferably from 10 to 30 seconds.

The magnetic field strength applied to the packed bed of shaped wateradsorbent composite bodies is typically tailored to the shape, size andconfiguration of that packed bed. In embodiments, the magnetic fieldstrength is at least 10 mT, preferably at least 12 mT, preferably about12.6 mT. However, it should be appreciated that the selected magneticfield strength depends on the particular application, and is generallyselected to provide the lowest power consumption and thus lowestmagnetic field strength for the maximum heat to desorb water from thewater adsorbent MOF. The frequency of the AC magnetic field can beselected to provide maximum heating. In embodiments, the frequency ofthe AC magnetic field is between 200 and 300 kHz, preferably between 250and 280 kHz, and more preferably from 260 to 270 kHz. Again, thefrequency can be selected for a particular application and betailored/optimised to provide the greatest heating for the lowest powerconsumption.

Again, it should be appreciated that the water containing gas cancomprise any number of gases, such as nitrogen, oxygen or the like. Inembodiments, the water containing gas comprises air, preferablyatmospheric air, more preferably ambient air. The method can thereforeby used to separate and capture water content from atmospheric air andthereby capture water.

The condenser system is used separate the water content of the productfluid flow (typically gas with entrained water vapour) to produce water.It is to be understood that a large variety of condenser arrangementsare possible, and are selected to meet the particular requirements of adesigned system. The condenser is used to convert water vapour in theproduct fluid flow into liquid water. In some embodiments, the condensercomprises a heat transfer/cooling device such as a cooling trap, aircoils, surface condensers or another heat exchange device.

In some embodiments, the metal organic framework adsorbent can beactivated before use (i.e. use for moisture adsorption) by triggeringthem by heating the composite bodies and passing (feeding) a drynitrogen stream through the column. Where the water adsorbent comprisescomposite bodies that include magnetic particles, heating can beachieved with an alternating current magnetic field. Activation of thematerial was performed until the humidity of the out coming gas streamwas zero.

Overall, the method and associated apparatus has a water productioncapacity of at least 2.8 L/kg of MOF, more preferably at least 3.5 L/kgof MOF, yet more preferably at least 4 L/kg of MOF, and in someembodiments about 4.1 L/kg of MOF at 20% RH and 35° C. The typicalenergy use is between 10 and 15 kWh/L, typically around 12 kWh/L waterproduced.

Temperature Swing Apparatus for Capturing Water from a Water ContainingGas

A third aspect of the present invention provides an apparatus forcapturing a water content from a water containing gas, the apparatuscomprising:

at least one heat transfer arrangement in contact with a packed bed ofshaped water adsorbent composite bodies having at least one meandimension of greater than 0.5 mm and comprising at least 50 wt % wateradsorbent metal organic framework; and at least 0.1 wt % hydrophilicbinder comprising a hydrophilic cellulose derivative; and

at least one peltier device in thermal communication with each heattransfer arrangement, each peltier device being configured to heat theshaped water adsorbent composite bodies to desorb water therefrom to beentrained into a product fluid flow,

wherein at least one peltier device also forms part of a condensersystem for cooling the product fluid flow from the packed bed of shapedwater adsorbent composite bodies.

This third aspect of the present invention provides a water capturingapparatus that includes shaped water adsorbent composite bodies thatuses temperature swing induction heating to desorb water adsorbed withinand on the shaped bodies. In this aspect, the shaped bodies arecollected in a packed bed that is enclosed in contact with a heat sink.The apparatus also includes peltier device configured to heat the packedbed of shaped water adsorbent composite bodies to release adsorbed waterfrom the packed bed of shaped water adsorbent composite bodies whenactivated. The peltier device is also configured to provide a coolingfunction to drive condensation of the fluid flow that is desorbed fromthe shaped water adsorbent composite bodies of the packed bed.

As noted above in relation to the first aspect, the peltier device ispreferably selected to be suitable to provide sufficient energy todesorb water from the shaped water adsorbent composite bodies. Thepeltier device is therefore selected to have a maximal heat flow of atleast 50 W, preferably at least 75 W, more preferably at least 100 W,and yet more preferably at least 110 W. Furthermore, the peltier devicecan be selected to be able to heat the packed bed to at least 50° C.,preferably at least 60° C., more preferably to at least 65° C., and morepreferably to at least 70° C. In some embodiments, peltier device isselected to be able to heat the packed bed to between 50 and 90° C.,preferably between 50 and 80° C., more preferably between 50 and 80° C.,yet more preferably between 65 and 85° C. In some embodiments, peltierdevice is selected to be able to heat the packed bed to between 70 and80° C., and preferably around 75° C.

The shaped water adsorbent composite bodies can be located around,within or in any number of other configurations in contact with the heattransfer arrangement. In preferred embodiments, the shaped wateradsorbent composite bodies are located within the heat transferarrangement.

Again, the heat transfer arrangement can have any number of forms,including a variety of heat exchanger configurations. In a number ofembodiments, the heat transfer arrangement comprises a heat sink (i.e. aconductive heat transfer arrangement), preferably a heat sink having aplate or fin arrangement. In some embodiments, the heat sink arrangementcomprises a plurality of spaced apart heat transfer elements. In thisarrangement, the shaped water adsorbent composite bodies are fitted as apacked bed between at least two heat transfer elements. The heattransfer elements typically comprise at least one of plates or fins.

Adsorption and desorption from the shaped water adsorbent compositebodies can be enhanced by driving fluid flow through and over the shapedwater adsorbent composite bodies. In some embodiments, the apparatusfurther includes at least one fluid displacement device to drive fluidflow through the packed bed. The fluid displacement device preferablycomprises at least one fan. Flow can be driven through the packed bed ata number of flow rates. In order to optimise water adsorption anddesorption, the fluid displacement device preferably creates a fluid ofat least 3 m³/hr, preferably 3 to 300 m³/hr, and more preferably 3 m³/hrto 150 m³/hr through the packed bed. It should be appreciated that theamount of air required to flow through the packed bed depends on themoisture level in the water containing gas and the efficacy of capture.

When operated, each peltier device develops a hot side and a cold side(as described in more detail in the detailed description). In thisarrangement, the hot side of each peltier device is preferably inthermal communication with at least one heat sink, and the cold side ofeach peltier device forms part of the condenser system.

The condenser system may also include a heat transfer arrangement toassist in heat transfer from the surrounding gases to the cold side ofthe peltier device. In embodiments, the cold side of each peltier deviceis in thermal communication with at least one heat transfer arrangement.Similar to the hot side, the heat transfer arrangement preferablycomprises a heat sink (a conductive heat transfer arrangement), and morepreferably a heat sink having a plate or fin arrangement.

A fourth aspect of the present invention provides a method of capturinga water content from a water containing gas using the apparatusaccording to the third aspect of the present invention. The methodcomprises at least one cycle of:

feeding a water containing gas through the packed bed of shaped wateradsorbent composite bodies of said apparatus such that the shaped wateradsorbent composite bodies adsorb water from the water containing gas;

operating the at least one peltier device to heat the shaped wateradsorbent composite bodies so to release at least a portion of theadsorbed water therefrom into a product fluid flow; and directing theproduct fluid flow to the condenser system to separate a water contentfrom the product fluid flow.

It should be understood that operation of the at least one peltierdevice to heat the shaped water adsorbent composite bodies creates aheat from through the peltier device from the cold side to the hot sidethereof. Operation of the at least one peltier device therefore alsocauses the cold side of each peltier device to operate (turn on), andthereby commencing operation of the condenser system via the cold sideof the peltier devices which form part of the condenser system.

It is to be understood that this method is a cyclical method, where thesteps of adsorbing water in the shaped water adsorbent composite bodies,releasing that adsorbed water through heating from the at least onepeltier device and condensing that water is conducted in a repetitivecycle so to continuously produce water. The cycle time typically dependson configuration of the packed bed and the adsorption system, the amountof shaped water adsorbent composite bodies, the depth of the packed bed,breakthrough point, saturation point and characteristics of theparticular pack bed, temperature, pressure, heat sink configuration, thepeltier device and other process conditions. In some embodiments, thecycle time of this method steps are approximately 6 hours in duration.However, other cycle times between 1 hour to 24 hours could be possibledepending on the configuration of the apparatus and packed bed andprocess conditions.

The condenser system is used separate the water content of the productfluid flow (typically gas with entrained water vapour) to produce water.It is to be understood that a large variety of condenser arrangementsare possible, and are selected to meet the particular requirements of adesigned system. The condenser is used to convert water vapour in theproduct fluid flow into liquid water. In some embodiments, the condensercomprises a heat transfer/cooling device such as a cooling trap, aircoils, surface condensers or another heat exchange device.

Magnetic Swing Apparatus for Capturing Water from a Water Containing Gas

A fifth aspect of the present invention provides an apparatus forcapturing a water content from a water containing gas, the apparatuscomprising:

a housing containing therein a packed bed of shaped water adsorbentcomposite bodies having at least one mean dimension of greater than 0.5mm and comprising at least 50 wt % water adsorbent metal organicframework; at least 0.1 wt % hydrophilic binder comprising a hydrophiliccellulose derivative and from 0.2 to 10 wt % magnetic particles having amean particle diameter of less than 200 nm; and

an alternating current (AC) magnetic field generator located withinand/or around the packed bed of shaped water adsorbent composite bodiesconfigured to apply an AC magnetic field to the packed bed of shapedwater adsorbent composite bodies.

This fifth aspect of the present invention provides a water capturingapparatus that includes shaped bodies that uses magnetic swing inductionheating to desorb water adsorbed within and on the shaped bodies. Inthis aspect, the shaped bodies are collected in a packed bed that isenclosed in the housing. The housing is preferably a fluid tighthousing. The apparatus also includes an alternating current magneticfield generator designed to irradiate the packed bed of shaped wateradsorbent composite bodies with an AC magnetic field to release adsorbedwater from the packed bed of shaped water adsorbent composite bodieswhen activated. The apparatus is configured to enable the shaped wateradsorbent composite bodies to undergo magnetic induction swingadsorption to capture water from a water containing gas fed into thepacked bed of shaped water adsorbent composite bodies.

Any AC magnetic field generator can be used which is capable of applyinga localised AC magnetic field to the packed bed of shaped wateradsorbent composite bodies. In some embodiments, the AC magnetic fieldgenerator comprises at least one induction coil located within and/oraround the packed bed of shaped water adsorbent composite bodies.Preferably, one or more induction coils are embedded within andsurrounded by the shaped water adsorbent composite bodies in the packedbed so to use the whole magnetic field generated by the induction coilor coils. In some embodiments, the induction coil or coils areconfigured to sit within a central section of the packed bed, occupyingfrom 50% to 90%, preferably from 70 to 80% of the axial height (depth)of the packed bed.

The housing has a fluid inlet and a fluid outlet through which a fluid,preferably the moisture containing gas and product fluid is configuredto flow. The housing can have any suitable configuration. In someembodiments, the housing comprises a container or canister, for examplea substantially cylindrical container or canister. The housing ispreferably fluid tight, with only fluid access and egress through theinlet and outlet of that housing. In other embodiments, the housingcomprises a flat, high surface area container. It should be appreciatedthat a variety of container and canister shapes and configurations couldbe used. The housing may be exchangeable or is installed fixed in thesystem.

The plurality of said shaped water adsorbent composite bodies ispreferably arranged in the housing in a packed bed system. The housingcan include two spaced apart support membranes configured to allow gasflow therethrough each membrane, the plurality of said shaped wateradsorbent composite bodies forming a packed bed therebetween andpreferably being compressed therebetween. The apparatus of this fifthaspect can further include a condenser system for cooling a fluid flowfrom the packed bed of shaped water adsorbent composite bodies. Avariety of condensers can be used. In embodiments, the condensercomprises a cooling device, for example a cooling trap.

The Inventors have found that potable water can be expeditiouslyproduced using the apparatus of this aspect of the present invention.This apparatus utilises a packed bed of the shaped water adsorbentcomposite bodies of the first aspect of the present invention in amagnetic induction vacuum swing adsorption system to separate and thuscapture water from an water bearing gas (such as humid air) and releaseand harvest that captured content using a condenser.

A sixth aspect of the present invention provides a method of capturing awater content from a water containing gas using the apparatus accordingto the fifth aspect of the present invention, comprising at least onecycle of (the steps of):

feeding a water containing gas through the packed bed of shaped wateradsorbent composite bodies of said apparatus such that the shaped wateradsorbent composite bodies adsorb water from the water containing gas;

applying an alternating current magnetic field to the shaped wateradsorbent composite bodies using the alternating current magnetic fieldgenerator of said apparatus, thereby generating heat within the shapedwater adsorbent composite bodies, so to release at least a portion ofthe adsorbed water therefrom into a product fluid flow; and

directing the product fluid flow to a condenser to separate a watercontent from the product fluid flow.

In this sixth aspect of the present invention a moisturized gas streamis fed through a packed adsorption column. After the absorbent ischarged with water vapour, an alternating current magnetic field isapplied. Consequently, the pellets start heating up rapidly forcing thewater to be released. The desorbed water is condensed in a condenser,for example in a cold trap. This method therefore takes advantage of thehigh energy conversion efficiency of magnetic induction heating. Inembodiments, the apparatus and method has an energy conversionefficiency of greater than 90%, preferably greater than 95% and in someembodiments up to 98% was achieved. Furthermore, the use of rapidheating through magnetic induction heating enables short cycle times tobe achieved.

It is to be understood that this method is a cyclical method, where thesteps of adsorbing water in the shaped water adsorbent composite bodies,releasing that adsorbed water through application of the AC magneticfield and condensing that water is conducted in a repetitive cycle so tocontinuously produce water. The cycle time typically depends on theconfiguration of the packed bed and the adsorption system, the amount ofshaped water adsorbent composite bodies, the depth of the packed bed,breakthrough point, saturation point and characteristics of theparticular pack bed, temperature, pressure and other process conditions.In some embodiments, the cycle time of this method steps areapproximately 30 minutes in duration. However, other cycle times between10 minutes to 2 hours could be possible depending on the configurationof the apparatus and packed bed and process conditions.

Method of Forming Shaped Water Adsorbent Composite Body

The present invention can also provide a method of forming a shapedwater adsorbent composite body for the adsorption system of the firstaspect. The method comprises the steps of:

preparing a composite powder mixture comprising at least 50 wt % wateradsorbent metal organic framework; at least 0.1 wt % hydrophilic bindercomprising a hydrophilic cellulose derivative; and optionally 0.2 to 10wt % magnetic particles having a mean particle diameter of less than 200nm;

preparing a composite paste comprising a mixture of the composite powdermixture and a solvent;

forming the composite paste into a shaped body having at least one meandimension of greater than 0.5 mm; and

heating the shaped body to substantially remove the solvent from theshaped body,

thereby producing a shaped water adsorbent composite body for use in apacked bed adsorption system.

This aspect of the present invention provides a method of forming theshaped water adsorbent composite body used in various embodiments of thepresent invention. In this method, the composite powder mixture(typically a pulverulent material) comprising a powder mix of metalorganic framework and a hydrophilic binder, is formed into a paste usinga solvent, which can then be shaped, for example by extrusion orpalletising processes into the desired shaped body.

The solvent used to form the shaped body can be any suitable solventthat has good interaction with the constituents of the composite powdermixture. Suitable solvents are preferably selected from a non-basicpolar solvent and/or a non-self ionising polar solvent. The solventpreferably comprises an alcohol, such as methanol, ethanol, C2-C9alcohols including their branched isomers, or water, more preferablydeionised water.

The hydrophilic binder and a liquid solvent are added to the compositepowder mixture to assist in the formation of a suitable paste forshaping processes. It should be appreciated that the composite pastecomprises a thick, soft, moist mixture. The paste preferably hassufficient viscosity to retain a form when shaped into a desiredconfiguration in the forming/shaping step. The amount of solvent andcomposite powder material (a pulverulent material, preferably powder orparticulates) is typically mixed to provide a suitable paste consistencyfor shaping processes such as extrusion or pelletising.

It is also important to appreciate that the shaped body preferablycomprises the water adsorbent MOF and the hydrophilic binder. Thesolvent is purely used to form the paste which is evaporated orotherwise removed from the shaped composite material during the heattreatment step.

Magnetic particles can also be included in the formed shaped compositematerial. In these embodiments the composite powder mixture furthercomprises from 0.2 to 10 wt % magnetic particles having a mean particlediameter of less than 200 nm.

The composite paste can be formed into the shaped body using a varietyof processes. In embodiments, forming the composite paste into a shapedbody comprises at least one of extruding, pelletising or moulding thecomposite paste into a desired three-dimensional configuration.Preferred methods include rod extrusion or tableting. Where the shapedbody is formed by an extrusion or similar process such that thecomposite paste is extruded into an elongate body, that elongate body ispreferably subsequently longitudinally divided, typically to a lengthsuitable used in a packed bed of a packed bed adsorption system. It ispreferred that after extrusion the extruded elongated body is allowed todry, for example air dry, for a period of time prior to beinglongitudinally divided. That drying time can vary, but is typically atleast 10 minutes. Afterwards, the extruded body is cut into 3 to 5 mmlong shaped bodies, preferably pellets.

The shaping step can be performed in the presence of lubricants and/orother additional substances that stabilize the materials to beagglomerated. Suitable lubricants include surfactants and their salts.Examples of suitable lubricants include magnesium stearate, aluminiumoxide, sodium oleate, glycerides, di-glycerides, tri-glycerides, fattyacids, oils including silicon oils and mineral oils and mixturesthereof. It should be appreciated that the additives depend on theapplication in which the shaped bodies are being used. The lubricantspreferably comprise an approved excipient for human consumption wherewater is being produced for human consumption. Examples of approvedexcipients for human consumption include approved excipients for food orpharmaceuticals. Approved food grade or pharmaceutical grade lubricantsare preferred. As discussed below, lubricants are added to the mixtureto assist with shaping and forming processes when making the shapedbody. In some embodiments, the lubricant can be mixed in the powdermixture with the binder to form part of the powder mixture. In otherembodiments, the lubricant is applied to the surface of the shapingdevice, for example an extruder or pelletiser, to lubricate the outersurface only. The resulting shaped water adsorbent composite bodypreferably comprises less than 0.5 wt % lubricant, preferably less than0.1 wt % lubricant.

The shaped body/bodies are preferably formed with dimensions that aresuitable for use in a packed bed adsorption system, in which a pluralityof the shaped bodies are packed at a high packing density 0.10 to 0.5kg/L, preferably 0.25 to 0.4 kg/L between two support surfaces. Thedimensions of the shaped body can be optimised to suit this application.The shaped water adsorbent composite body has at least one meandimension of greater than 0.5 mm when used in a packed bed adsorptionsystem. This ensures the adsorbent composite body has sufficient size toallow gas flow around. For example, fine powder (for example having anaverage particle size of less than 10 micron) provides too dense packingfor use in a packed bed of a packed bed adsorption system. In someembodiments, the shaped body has at least one mean dimension of greaterthan 0.8 mm, preferably at least 1 mm, preferably at least 1.2 mm, andyet more preferably at least 1.5 mm. Preferably, each of the mean width,mean depth and mean height of the shaped body are greater than 0.5 mm,and preferably greater than 1 mm.

The shaped body can be formed to have any suitable geometry. The shapeof the shaped water adsorbent composite body has an impact on thepressure drop of local fluid flow (in the vicinity of the bodies), andtherefore, the performance of any packed bed adsorption system. Forexample, the shaped body could comprise pellets, for example,disk-shaped pellets, pills, spheres, granules, extrudates, for examplerod extrudates, honeycombs, meshes or hollow bodies. In embodiments, theshaped body is three dimensional, preferably three dimensionally shaped.In particular embodiments, the shaped body comprises an elongate bodyhaving a circular or regular polygonal cross-sectional shape. Inpreferred embodiments, the shaped body comprises a triangularcross-sectional shape, and more preferably an equilateral trianglecross-sectional shape. For example, the shaped body may have a square ortriangular cross-sectional shape. In one form, the shaped body hasequilateral triangle cross-section, preferably the sides of theequilateral triangle are at least 1 mm in length, preferably between 1.0and 1.5 mm in length. The elongate shaped body is preferably from 1 to 5mm in length (longitudinal length), more preferably 1 to 4 mm in length.In some embodiments, the elongate shaped body is 3 to 5 mm in length.

The heating step is preferably conducted for sufficient time to removethe solvent from the shaped body. The heating step is preferablyconducted at a temperature of between 80 to 150° C., preferably between90 and 120° C. The heating step can be conducted for at least 1 hour,preferably at least 2 hours, more preferably at least 5 hours, yet morepreferably at least 8 hours, and yet more preferably at least 10 hours.Similarly, the pressure is selected to assist solvent removal. Inembodiments, the pressure is less than 100 mbar, preferably less than 50mbar, more preferably less than 35 mbar. In other embodiments, thepressure is less than 500 mbar. In some embodiments, the heating step isconducted in an insert gas atmosphere, for example nitrogen or argon.

The heating step can include an additional activation step where theshaped adsorption body/bodies are dried at an elevated temperature toensure the pores of the water adsorbent MOF are free of moisture orsolvent. In some embodiments, this activation heating step comprisesheating the shaped adsorption body to at least 120° C., preferablybetween 120 and 150° C. for at least 5 hours, preferably at least 6hours, more preferably from 6 to 10 hours, and more preferably from 6 to8 hours. The activation heating step is preferably conducted at areduced pressure of less than 200 mbar, preferably less than 100 mbar,and more preferably less than 50 mbar. In some embodiments, the shapedadsorption body is heated to a temperature of 130° C. at a pressure ofless than 200 mbar, preferably less than 100 mbar, more preferably lessthan 50 mbar to activate the MOF for 6 to 8 hours.

In other embodiments, the shaped adsorption bodies can be activated bytriggering them with an alternating current magnetic field within aninert gas flow, for example dry nitrogen stream. Activation of theshaped adsorption bodies can be performed until the humidity of theout-coming gas stream is zero.

After heating, the material is preferably cooled down to at most 80° C.,preferably at most 60° C. under reduced pressure of at most 500 mbar,preferably at most 100 mbar.

It should be appreciated that that water produced from the apparatus andmethod according to embodiments of the present invention can be used forany purpose, including but not limited to;

-   -   Water as a substrate for energy production or synthesis of        chemicals or the like;    -   Water for specialised use such as ultra-pure water for medical        or laboratory use or the like;    -   Water for use in defence or medical sectors;    -   Water for industrial applications such as farming, irrigation,        quenching fire or the like;    -   Water for consumption such as house hold use, bottled water,        food production or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to theFigures of the accompanying drawings, which illustrate particularpreferred embodiments of the present invention, wherein:

FIG. 1A is a schematic of a magnetic induction swing apparatus forcapturing a water content from a water containing gas according to oneembodiment of the present invention.

FIG. 1B is a schematic of a magnetic induction swing apparatus forcapturing a water content from a water containing gas according toanother embodiment of the present invention.

FIG. 1C is a schematic of a temperature swing apparatus for capturing awater content from a water containing gas according to one embodiment ofthe present invention which includes a heat sink (CPU cooler) andpeltier device.

FIG. 1D is a photograph of the experimental temperature swing apparatusfor capturing a water content from a water containing gas according toone embodiment of the present invention which includes a heat sink (CPUcooler) and peltier device.

FIG. 1E provides schematic diagrams of operation of the thermal cyclewater harvesting device shown in FIG. 1C when operated (A) during theadsorption phase; and (B) during the desorption phase.

FIG. 2A is a photograph of the experimental setup used for aluminiumfumarate synthesis.

FIG. 2B is a photograph of the produced aluminium fumarate after washingprocedure.

FIG. 2C provides a schematic diagram of a shaped adsorption body cordingto one embodiment of the present invention utilised in the packed bed ofthe apparatus shown in FIGS. 1A to 1D.

FIG. 3A is photograph of the hand extruder and triangular shaped nozzleused to produce the shaped aluminium fumarate composite pellets.

FIG. 3B provides a schematic diagram of the pellet forming process.

FIG. 4 is a photograph showing the produced aluminium fumarate andaluminium fumarate composite pellets, being (A) Pristine MOF; (B) 1 wt %binder; (C) 1 wt % MNP; (D) 3 wt % MNP; and (E) 5 wt % MNP.

FIG. 5 is a schematic of the experimental setup used for inductionheating experiments.

FIG. 6 is a schematic of the experimental magnetic induction swing watercapturing rig.

FIG. 7 provides a PXRD pattern of aluminium fumarate, simulatedaluminium fumarate and aluminium fumarate with 1 wt % binder (Batch I).

FIG. 8 provides a PXRD pattern of different aluminium fumarate magneticcomposites, aluminium fumarate with 1 wt % binder (Batch I) andmagnesium ferrite as reference.

FIG. 9 provides a PXRD pattern of aluminium fumarate magnetic composite,aluminium fumarate (Batch II) and magnesium ferrite as reference.

FIG. 10 provides a SEM image of aluminium fumarate metal organicframework (Batch II). Magnification: 10000 times.

FIG. 11 provides a SEM image of magnesium ferrite nanoparticles.Magnification: 10.000 times.

FIG. 12 provides a SEM image of aluminium fumarate magnetic frameworkcomposite (Batch II) at a magnification of 10000 times. The circledsections marked with A indicate the location of magnesium ferritenanoparticles in the composite.

FIG. 13 provides an averaged BET surface area of aluminium fumaratecomposites as a function of magnetic nanoparticle loading.

FIG. 14 provides a plot of the pore size distribution of aluminiumfumarate MOF pellets (Batch I).

FIG. 15 provides a nitrogen isotherm of aluminium fumarate pellets.

FIG. 16 provides a plot of the pore size distribution of aluminiumfumarate composite pellets containing: (a) 1 wt % binder. (b) 1 wt %MNPs (c) 3 wt % MNPs (d) 5 wt % MNPs.

FIG. 17 provides water vapour adsorption isotherms for aluminiumfumarate batch I and aluminium fumarate batch I composite pelletscollected at room temperature.

FIG. 18 provides water vapour adsorption isotherms of aluminium fumaratebatch II and aluminium fumarate batch II composite pellets collected atroom temperature.

FIG. 19 provides a plot of the initial heating rate of induction heatingof Aluminium Fumarate magnetic framework composites with different MNPconcentrations. Field strength was 12.6 mT.

FIG. 20 provides a plot of the efficiency of induction heating ofAluminium Fumarate magnetic framework composites with different MNPloading. Field strength was 12.6 mT.

FIG. 21 provides a plot of the normalized relative humidity over timefor adsorption of water vapour from a nitrogen stream.

FIG. 22 provides a plot of the temperature profile of aluminium fumaratecomposites during adsorption of moisture.

FIG. 23 provides a plot of the normalized relative humidity over timefor the out coming stream during regeneration.

FIG. 24 provides a plot of the temperature profile of aluminium fumaratecomposites during regeneration of water vapour.

FIG. 25 provides a plot comparing the water vapour uptake isotherms of(A) a first batch of AlFu (Aluminium Fumarate (I)); (B) pelletscomprising Aluminium Fumarate (I) and a cellulose siloxane binder; (C) asecond batch of AlFu ((Aluminium Fumarate (II)); and (D) pelletscomprising Aluminium Fumarate (II) and a hydroxypropyl cellulose binder.

FIG. 26 illustrates the setup of the testing rig for the temperatureswing water harvesting device shown in FIGS. 1C and 1D, including withpower supplies and measurement equipment.

FIG. 27 illustrates the FTIR pattern of aluminium fumarate with 1 wt %binder after the pelletisation process for each of the three batches(batch_01, batch_02 and batch_03) and t the FTIR pattern of pristinealuminium fumarate.

FIG. 28 illustrates the PXRD pattern of pristine aluminium fumarate andaluminium fumarate with 1 wt % binder of all three extrusions after thepelletisation process. Simulated pattern for comparison.

FIG. 29 illustrates water uptake isotherms at 26° C. of aluminiumfumarate pellets produced in this work (Pellets_02) (squares), andliterature data of aluminium fumarate from Teo et al. [28] (diamonds).

FIG. 30 illustrates mass logging of an adsorption phase with a humidityof 8:85 μm⁻³. This data is used to calculate theoretical adsorptiontimes for all water harvesting cycles.

FIG. 31 illustrate the optimisation of the condensation time of thewater harvesting device plotting space time yield and specific energyover different condensation times corresponding to water harvestingcycles 12, 14, 15, 16 and 17.

FIG. 32 illustrates optimisation of the desorption temperature of thewater harvesting device plotting space time yield and specific energyover different desorption temperatures corresponding to water harvestingcycles 16, 18, 19 and 20.

FIG. 33 illustrates temperature and relative humidity of the adsorptionof water harvesting cycle 16.

FIG. 34 illustrates the temperatures in the water harvesting deviceduring the desorption phase of water harvesting cycle 16.

FIG. 35 illustrates the relative humidity, dew point and condensertemperature in the water harvesting device during the desorption phaseof water harvesting cycle 16.

FIG. 36 illustrates the temperature and relative humidity of theadsorption of water harvesting cycle 24.

FIG. 37 illustrates the temperatures in the water harvesting deviceduring the desorption phase of water harvesting cycle 24.

FIG. 38 illustrates the relative humidity, dew point and condensertemperature in the water harvesting device during the desorption phaseof water harvesting cycle 24.

FIG. 39 illustrates the temperature and relative humidity of theadsorption of water harvesting cycle 22.

FIG. 40 provides two views of a prototype water capture apparatus usingthe temperature swing water harvesting embodiment showing (A) externalhousing; and (B) inner components, including louver system.

DETAILED DESCRIPTION

The present invention provides an apparatus that provides selectivecontrol of the adsorbing and desorbing phases of a MOF based wateradsorbents water harvesting cycle. The apparatus includes a waterdesorption arrangement which allows the MOF based water adsorbent toadsorb water when in a deactivated state, and then apply desorptionconditions to the water adsorbent to desorb water from the wateradsorbent when in an activated state. This selective operation of thewater desorption arrangement between the deactivated and activatedstates enables the efficiency of water desorption arrangement to beoptimised using more efficient energy desorption arrangements to desorbwater from the metal organic framework based water adsorbent comparedfor example to utilising solar energy, and in some embodiments that cansimultaneously condense the water content of any product gas flow.

Adsorption Apparatus

The water desorption arrangement can take any number of forms dependingon whether heat and/or reduced pressure is being used to cause theadsorbed water to desorb from the water adsorbent. In some embodiments,the apparatus is designed for pressure swing adsorption, with desorptionbeing achieved by reducing the pressure for example using a vacuum pumpto evacuate the gas from around the water adsorbent. Adsorption wouldtypically be undertaken at near atmospheric pressure. In otherembodiments, temperature swing adsorption is undertaken to achieve waterharvesting. This can be achieved using direct heating methods, or insome cases using magnetic induction swing adsorption.

Magnetic Swing Water Adsorption Apparatus

In some cases, the apparatus can be configured as a magnetic swing wateradsorption apparatus to harvest a water content from a water containinggas, such as atmospheric air. One form of this type of apparatus 200 isillustrated in FIG. 1A or 1B.

FIGS. 1A and 1B illustrate an apparatus 200 for capturing a watercontent from a water containing gas that uses a shaped water adsorbentcomposite body formulated with magnetic particles as discussed above.The apparatus 200 comprises a cylindrical housing 205 which includesinlet 208 and outlet 211. Housing 205 contains a packed bed 215 ofshaped water adsorbent composite bodies 100 (see FIG. 2C), thecomposition of which is described in more detail below. A fluiddistributor disc 210 proximate the base and lid/top of the housing 205is used to retain the shaped adsorption material 215 between the discs205. Each fluid distributor disc 210 comprises a metal disc withmultiple holes drilled therethrough to allow fluid to flow through thepacked shaped adsorption material. The shaped adsorption material formsa compressed packed bed between the discs 210, and are compressedtherebetween so that the adsorbent shaped bodies 100 are tightly packedtherein, thereby avoiding any flow short circuiting.

In the embodiment shown in FIG. 1A, an alternating current (AC)induction coil 250 is located within and surrounded by the packed bed215 of shaped water adsorbent composite bodies 100 (FIG. 2C). Theinduction coil 250 is configured to apply an AC magnetic field to thepacked bed 215 of shaped water adsorbent composite bodies. The inductioncoil 250 is embedded within the packed bed 215 to optimise the use ofthe applied magnetic field when the induction coil 250 is operated.

The housing 205 includes magnetic dampening material 255 to reducemagnetic field leakage from the container to the surroundings. This canbe important in some applications where a magnetic field coulddeliriously affect the operation of proximate equipment, or irradiatepeople or objects.

In the embodiment shown in FIG. 1B, an alternating current (AC)induction coil 250 is located external of the housing 205, but in alocation around the housing which extends around the packed bed 215 ofshaped water adsorbent composite bodies 100. Again, the induction coil250 is configured to apply an AC magnetic field to the packed bed 215 ofshaped water adsorbent composite bodies. However, it should beappreciated that the positioning of this induction coil 250 is not asenergy efficient as shown in FIG. 1A due to losses through the materialof housing. Furthermore, whilst not shown in FIG. 1B, a further housingmay be used to enclose the induction coil which includes magneticdampening material 255 to reduce magnetic field leakage to thesurroundings.

In use, a water containing gas is flowed through the packed bed ofshaped bodies 215 such that the shaped water adsorbent composite bodiesadsorb water from the water containing gas. Once the packed bed 215reaches a desired saturation (typically 70 to 90% saturation point), theinduction coil 250 is operated to apply an alternating current magneticfield thereby generating heat within the shaped water adsorbentcomposite bodies, so to release at least a portion of the adsorbed watertherefrom into a product fluid flow. The shaped water adsorbentcomposite bodies therefore undergo magnetic induction vacuum swingadsorption to capture water from the water containing gas fed into thepacked bed of shaped water adsorbent composite bodies 215.

Whilst not shown in FIG. 1A or 1B, a condenser can be used tosubsequently separate the water content of the product fluid flow(typically gas with entrained water vapour) to produce a captured waterproduct. A low or reduced pressure (sometimes referred to as a vacuumenvironment), or a positive pressure gas flow, for example a flow of thewater containing gas or another gas such as an inert or other dry gas,to direct the released water to the condenser.

The above described method is cyclically applied, where the steps ofadsorbing water in the shaped water adsorbent composite bodies 100,releasing that adsorbed water through application of the AC magneticfield and condensing that water is conducted in a repetitive cycle so tocontinuously produce water.

Temperature Swing Water Adsorption Apparatus

A temperature swing water harvesting apparatus 300 configured inaccording to an embodiment of the present invention is illustrated inFIGS. 1C, 1D and 1E.

The apparatus 300 shown in FIGS. 1C and 1D is configured to use thewaste heat of a peltier device 310 to heat up shaped MOF compositebodies 100 (the composition of which is described in more detail below)placed in thermal contact with the hot side 312 of the peltier device310 (via a heat sink 320, discussed below) to facilitate desorption ofadsorbed water in the shapes MOF composite bodies. The cold side 314 ofthe peltier device 310 can be simultaneously used to condense thedesorbed water vapour, and that condensed water can be collected as aliquid product below the peltier device 310.

Peltier Devices

A peltier device is a thermoelectric device with the ability to convertelectrical energy into a temperature gradient, generally termed the“peltier effect”. An electrical current applied to a pair of differentmetal materials leads to a hot surface on the one side and a coldsurface on the other side of the semiconductors and creates a heat flowthrough the semiconductors perpendicular to the current flow. A singlepair of a p- and n-type semiconductor material coupled in series issufficient to create a temperature gradient when a current is appliedfrom the n-type semiconductor to the p-type semiconductor. A cold sideof a peltier element is formed where the electrons flow from p- ton-type semiconductors and a hot side with the heat flow Q_(dis)appearing on the transition from n-type to p-type semiconductors. Itshould be appreciated that the dissipated heat of a peltier device ishigher than the electrical power due to the absorbed heat on the coldside of the peltier device.

Peltier devices are typically built of 3 up to 127 semiconductor pairsper device. The semiconductors are electrically connected in series andthermal in parallel. The heat flow in commonly available peltier devicesis between 1 W to 125 W. The temperature difference between the hot andcold side of a peltier device is up to 70K for single-stage devices andup to 130K for multi-stage devices (several peltier elements connectedin series).

Mechanical stress can occur in a peltier device due to the hightemperature difference and thus material expansion difference betweenthe cold and hot sides. The dimensions of peltier devices are thereforetypically limited to 50 by 50 mm to keep such mechanical stress issueslow. Current Peltier devices also suffer from a low efficiency of about10% of the possible Carnot efficiency due mainly to the availableproperties semiconductor material used in the specific peltier device.

Temperature Swing Desorption

FIGS. 1C and 1D illustrate an embodiment of the temperature swing waterharvesting apparatus 300. As shown, the device 300 comprises a sealablecontainer 330 having a container body 332 and sealing lid 334. Thecontainer body 332 houses which a polycarbonate plate 338 positioned andspaced away from the base of the container body 332 using spacers 339 todefine within the container 330 (i) an upper water adsorption-desorptionchamber 340; and (ii) a lower condenser chamber 342. The container 330is sealable using the removable sealing lid 334. Within the containerbody 332 sits a water harvesting device 350. The water harvesting device350 includes the following sections:

(A). A heat sink 320 including a plurality of spaced apart fins 352.Whilst not shown in detail, the space between each of the spaced apartfins 352 is filled with shaped water adsorbent composite bodies 100forming a packed bed 355 therein;

(B). A peltier device 310 having a hot side 312 in thermal communicationwith the heat sink 320 and a cool side 314 in thermal communication withthe gas space of the lower condenser chamber 342. The peltier device 310is configured to heat the shaped water adsorbent composite bodies 100 inthe heat sink 320 during a desorption phase of a water harvesting cycle(see below); and(C). A condenser system 360 located in the condenser 342, which uses thecool side 314 of the peltier device 310 to cool a fluid flow of watervapour that is produced from the packed bed 355 to condense and collectthe water as a liquid product at the base of the container 330.

The apparatus 300 shown in FIGS. 10, 1D and 1E utilise both the coldside 314 and hot side 312 of the peltier device 310 during thedesorption phase of a temperature swing water harvesting cycle. Thedissipated heat of the hot side 312 of the peltier device 310 can beused in a temperature swing desorption cycle to heat up the shaped MOFcomposite bodies 100 during the desorption phase to desorb water fromthe shaped MOF composite bodies 100. The cold side 314 can be used toadsorb heat from the produced water vapour, and condense that water in acondenser system/chamber, to enable water to be collected as a liquidproduct.

For this application, it should be appreciated that the key criteria inselecting the peltier device are:

-   -   Capability to provide sufficient heating so that at the hot side        of the peltier device water is desorbed from the MOF composite.    -   Capability to provide sufficient cooling for the cold side of        the peltier device to be below the dew point in the condenser        system for condensation to occur.    -   Other factors including reliability and resistance to corrosion.        The lowest powered peltier device to be able to this will result        in the highest efficiency device.

In the illustrated system (see FIG. 1D), the water harvesting device 350is mounted within a 10 L sealable food container. The heat sink 320comprises two NH-D15S (Rascom Computer distribution Ges.m.b.H., Wien(Austria)) CPU coolers. However, it should be appreciated that othersuitable heat sink configurations could equally be used. This type ofCPU cooler has a surface area of 1:0634 m² and a free volume of 0:9967L. This type of heat sink 320 is used as the dimensions of peltierdevices are limited to sizes of around 40 mm by 40 mm due to heat stressissues (as discussed previously). The heat sink 320 ensures heat isdistributed from the peltier device(s) 310 to a much larger surface,which can be used for conductive heat transfer to heat up the shaped MOFcomposite bodies in the packed bed 355.

The heat sink 320 has a mounting socket that fits perfectly onto apeltier device and conducts the heat with 12 heat pipes 356 to 90 metalfins 352. 45 fins 352 are stacked on top of each other with a distanceof 1:92 mm. Two of these heat sink 320 stacks are assembled side by sideonto the mounting socket of the heat sink 320. A 12 V fan 370 is mountedbetween the two heat sink 320 stacks to provide an air flow through thefree volume between the fins 352 during adsorption and desorption phase.However, it should be appreciated that the fan could be included inother locations proximate to the heat sink 320 stacks. The heat sink 320and the peltier device 310 are mounted onto the polycarbonate plate 338.The heat sink 320 is fastened onto the peltier device 310 using screws.Heat grease is applied on the connection surfaces between the peltierdevice 310 and the heat sink 320 to ensure sufficient heat flow throughthis connection. The fan 370 is selected to produce a flow rate from 3m³/hr to 200 m³/hr. In the illustrated embodiment, the fan comprises a12 V fan capable of flow rates up to 140 m³/hr. In most test runs it wasset on a low setting generating approximately 30 m³/hr. This flow ratecan be can be tuned according to the ambient humidity conditions

Whilst not illustrated, an additional small heat sink can be fixed tothe cold side 314 of the peltier device 310 to increase the surface areafor water condensation. It should be appreciated that the cold side 314of the peltier device 310 with the small heat sink forms the condensersystem 360 of the water harvesting device 350.

As indicated above, the free volume between the fins 352 is filled withthe shaped MOF composite bodies 100. In the illustrated embodiment(FIGS. 1C to 1E), the MOF composite bodies 100 comprise aluminiumfumarate triangle shaped pellets with a side length S=1:5 mm and alength L=3 mm (see FIG. 1 ). The heat sink 320 is sealed with a netting(not illustrated) having a small enough aperture to retain the pelletsbetween the fins 352 of the heat sink 320. The netting comprises acommercially available fly wire having an aperture of 1 mm. 200.30 g MOFpellets are packed between the fins 352. This equals a packing densityof 0:20 kg/L. Thus 198:30 g of aluminium fumarate is used as adsorbentin the water harvesting device 350.

In the illustrated test rig (see FIG. 1D and FIG. 26 ), sixthermocouples 375 are fixed into the heat sink 320 to observe thetemperature and the temperature distribution in the MOF packed bed 355during the desorption phase. All six thermocouples are placed in one ofthe two sides of the heat sink 320. Three of the thermocouples are inthe centre of the fins 352 in three different heights. The other threethermocouples are on the right side of the fins 352 in three differentheights.

A water harvesting cycle (WHC) using this apparatus 600 can be designedwith two phases:

1. An Adsorption Phase (FIG. 1E(A)) —during which the sealable container330 is opened to the environment (i.e. lid 334 removed) and air is blownthrough the MOF packed bed 355 in the heat sink 320 using the fan 370.Water in the air is adsorbed by the shaped water adsorbent compositebodies 100 of the packed bed 355. During this phase, the peltier device310 is switched off. Once the packed bed 355 reaches a desiredsaturation (typically 70 to 90% saturation point), the lid 334 is placedon the container body 332 to seal the container 330 and the peltierdevice 310 is switched on to start the desorption phase.2. A Desorption Phase (FIG. 1E(B)) —where the peltier device 310 isswitched on and the packed bed 355 in the heat sink 320 is heated up toelevated temperatures so to release at least a portion of the adsorbedwater from the shaped water adsorbent composite bodies 100 in the packedbed 355 into a product fluid flow while the container 330 is sealedclosed. The relative humidity in the container 330 increases to highvalues and water condenses on the cold side 314 of the peltier device310. Liquid water is collected under the cold side 314 of the peltierdevice 310 after each water harvesting cycle.

The above described water harvesting cycle is cyclically applied, wherethe steps of adsorbing water in the shaped water adsorbent compositebodies 100, releasing that adsorbed water through operation of thepeltier device and condensing that water is conducted in a repetitivecycle so to continuously produce water.

Adsorption Medium

The apparatus illustrated in FIGS. 1A to 1E each use a shaped wateradsorbent composite body 100 (FIG. 2C) in a packed bed as the wateradsorbent. However, it should be appreciated that the metal organicframework composite can be provided in an apparatus of the presentinvention in any form suitable to the particular apparatusconfiguration. The inventors envisage that this may be in any number ofcomposite forms including (but not limited to) shaped bodies (forexample pellets or extrusions), coatings, plates, sheets, strips or thelike.

Shaped Metal Organic Framework Composite Body

The shaped water adsorbent composite body 100 (FIG. 2C) used in theapparatus discussed in relation to the apparatus shown in FIGS. 1A to 1Ecomprises a mixture of water adsorbent metal organic framework (MOF),and a hydrophilic binder which is optimised for use in a packed bedadsorption system. That mixture is composed of at least 50 wt % wateradsorbent metal organic framework and at least 0.1 wt % hydrophilicbinder.

In the embodiments shown in FIGS. 1A and 1B, the shaped water adsorbentcomposite body 100 is configured to harvest water using a magneticinduction swing adsorption system. In these embodiments, the shapedwater adsorbent composite body additionally contains from 0.2 to 10 wt %magnetic particles having a mean particle diameter of less than 200 nm.The use of magnetic particles in the composition forms enables inductiveheat generation to be used for water desorption. This type of composite,known as a magnetic framework composite, combines the exceptionaladsorption performance of MOFs and the high efficiency of magneticinduction heating.

The metal organic framework composite material can be shaped into anysuitable configuration for use in a packed adsorption system. In thepresent invention, the metal organic framework composite material isexemplified as a elongate shaped water adsorbent composite body 100having a triangular cross-section, for example as shown in FIG. 2C.However, it should be appreciated that other shapes for examplespherical, cylindrical, cubic, ovoid or the like could equally be used.

Referring to FIG. 2C, the shaped water adsorbent composite body 100comprises an elongate body having an equilateral trianglecross-sectional shape. The sides S of the equilateral triangle are atleast 1 mm in length, preferably between 1.0 and 1.5 mm in length. Theshaped water adsorbent composite body is preferably from 1 to 5 mm inlength (longitudinal length, L), more preferably 1 to 4 mm in length.The elongated triangular shape is selected to increase packing densityof the shaped water adsorbent composite bodies 100 within a packed bed(for example packed bed 215 shown in FIGS. 1A and 1B). Previous studieshave shown that this shape has one of the highest packing densities inpacked bed configurations. A high packing density is preferred foroptimum utilisation and heat generation from an applied heat source. Forexample, a cylindrical pellet shape has a packing density of around 0.19kg/L. An elongated equilateral triangular shaped pellet has a packingdensity of around 0.29 kg/L.

Water Adsorbent Metal Organic Framework

The water adsorbent metal organic framework used in the shaped wateradsorbent composite body 100 can be selected from a range of suitablewater adsorbent MOFs. A wide variety of water adsorbent MOFs are known,for example as discussed in Furukawa et al “Water Adsorption in PorousMetal-Organic Frameworks and Related Materials” Journal of the AmericanChemical Society 136(11), March 2014 and H W B Teo and A Chakraborty2017 IOP Conf. Ser.: Mater. Sci. Eng. 272 012019 the contents of whichshould be understood to be incorporated into this specification by thesereferences. In selected embodiments, the water adsorbent metal organicframework comprises at least one of aluminium fumarate, MOF-303 (Al),MOF-573 (Al), MOF-801 (Zr₆O₄(OH)₄(fumarate)₆), MOF-841(Zr₆O₄(OH)₄(MTB)₂(HCOO)₄(H₂O)₄), M₂Cl₂BTDD (including Co₂Cl₂BTDD),Cr-soc-MOF-1, MIL-101(Cr), CAU-10, alkali metal (Li+, Na+) dopedMIL-101(Cr), MOF-802 (Zr₆O₄(OH)₄(PZDC)₅(HCOO)₂(H₂O)₂), MOF-805(Zr₆O₄(OH)₄[NDC—(OH)₂]₆), MOF-806 (Zr₆O₄(OH)₄[NDC—(OH)₂]₆), MOF-808(Zr₆O₄(OH)₄(BTC)₂(HCOO)₆), MOF-812 (Zr₆O₄(OH)₄(MTB)₃(H₂O)₄) or a mixturethereof. Preferred water adsorbent metal organic frameworks arealuminium fumarate, MOF-303 (Al), MOF-801, MOF-841, M₂Cl₂BTDD,Cr-soc-MOF-1, and MIL-101(Cr).

Optimising the selection of a water adsorbing MOF involves a numberconsiderations, including:

-   1. Water stability—the MOF should be water stable.-   2. Adsorption reproducibility, the MOF should retain adsorption    capacity after multiple adsorption/desorption cycles, preferably at    least 10 cycles, more preferably at least 100 cycles.-   3. Ease of production, the MOF should be easy to produce from    readily available precursor materials.-   4. High water uptake from air even at low humidity values.-   5. A good affinity for water. The MOF should have a good enough    affinity for water to enable the MOF to adsorb the water, but not    have too high affinity for water that excessive energy needs to be    expended to desorb water therefrom. Here the thermodynamics of water    adsorption and desorption need consideration to ensure the MOF does    not require excessive energy (kJ/mol MOF) to desorb water therefrom,    and thereby adversely affect the energy efficiency of the system.    Typical heats of adsorption for water for the MOF range from 10 to    100 kJ/mol MOF for water adsorbed on the MOF (550 to 5500 kJ/kg).    Careful MOF selection is important to the operation of the device as    the cost of the water will be directly linked to the energy required    to desorb the water from the MOF.

Where the MOF is required for water production for human consumption,the MOF and other materials must also meet food for human consumptionregulations in relevant countries. The Applicant has found that thewater adsorbent MOF preferably comprises aluminium fumarate (AlFu) MOFin these embodiments. The water adsorption properties of AlFu arepublished in a number of research studies available in the publishedliterature.

Aluminium Fumarate

Aluminium fumarate (AlFu) is used as a preferred MOF in the shaped wateradsorbent composite body 100. The structure and water adsorptionproperties of AlFu are well known, for example as detailed in Teo et al.(2017). Experimental study of isotherms and kinetics for adsorption ofwater on Aluminium Fumarate. International Journal of Heat and MassTransfer Volume 114, November 2017, Pages 621-627, the contents of whichare to be understood to be incorporated into this specification by thisreference. As outlined in Teo, the crystal structure of AlFu resemblesMIL-53 as it also consists of infinite Al OH Al chains connected byfumarate linkers. AlFu has a permanently porous 3D structure of formula[Al(OH)(O₂C—CH═CH—CO₂)] with square channels.

Overall, aluminium fumarate was selected as a preferred choice of MOFfor the inventive water capturing apparatus and system due to:

-   1. Ease of manufacture—this MOF can be synthesised in water.    Following synthesis, processing the MOF is simple as outlined in the    Examples.-   2. Good thermal stability and is highly water stable (unlike many    other MOFs);-   3. It is robust to handling in ambient conditions and can withstand    multiple temperature cycles without degradation.-   4. It has a well-studied water adsorption behaviour;-   5. High water uptake from air even at low humidity values; Aluminium    fumarate has a water capacity between 0.09 to 0.5 grams of water per    gram of MOF depending on the relative humidity. The typical heat of    adsorption of Aluminium fumarate for water is well known and ranges    between 60 and 30 kJ/mol depending on the ambient humidity-   6. It can be cheaply and easily produced using non-toxic    constituents/precursor material—i.e. environmentally friendly    synthesis and is easy to handle and process; and-   7. Low cost of its constituents.

Nevertheless, it should be appreciated that the MOF component of thepresent invention is not restricted to Aluminium fumarate, and thatother water adsorbent MOFs can also be used in the composition of thewater adsorbent composite body.

Hydrophilic Binder

The selection of the appropriate binder is also important to the overallproperties of the shaped adsorption body. The inventors havesurprisingly found that a hydrophilic binder must be used to impartoptimal water adsorption properties to the shaped water adsorbentcomposite bodies. The inventors have also found that non-hydrophilicbinders and in particular hydrophobic binders (for example cellulosesiloxane) reduce/decrease the water adsorption properties of the shapedwater adsorbent composite bodies. The use of a hydrophilic binder istherefore important for optimal moisture capture properties of thepacked bed water adsorption system. However whilst other binders arealso possible, it is again noted that particularly suitable hydrophilicbinders can be selected from at least one of hydrophilic cellulosederivatives such as hydroxypropyl cellulose, hydroxyethyl methylcellulose, hydroxypropyl methyl cellulose (HPMC), ethyl hydroxyethylcellulose, methyl cellulose, or carboxymethyl cellulose (CMC) aspreviously set out in this specification. As indicated in the followingexamples, one exemplary hydrophilic binder is hydroxypropyl cellulose(HPC).

Lubricant

The shaped water adsorbent composite body can further comprise alubricant content, preferably less than 0.5 wt % lubricant, and morepreferably less than 0.1 wt % lubricant. Suitable lubricants includesurfactants and their salts. Examples of suitable lubricants includemagnesium stearate, aluminium oxide, sodium oleate, glycerides,di-glycerides, tri-glycerides, fatty acids, oils including silicon oilsand mineral oils and mixtures thereof. As mentioned previously, thelubricant content can assist with the shaping and forming processes ofthe shaped water adsorbent composite body.

Magnetic Particles

The shaped water adsorbent composite bodies can be configured to harvestwater using a magnetic induction swing adsorption system. In theseembodiments, the shaped water adsorbent composite body 100 (FIG. 1 )comprises a mixture composed of at least 50 wt % water adsorbent metalorganic framework, at least 0.1 wt % hydrophilic binder and from 0.2 to10 wt % magnetic particles having a mean particle diameter of less than200 nm. The mixture is optimised for use in a packed bed adsorptionsystem.

As discussed previously, a wide variety of magnetic particles can beused in the inventive shaped adsorption body. In embodiments, themagnetic particles comprise a ferromagnetic, paramagnetic, orsuperparamagnetic particles (typically micro or nano-particle). Inembodiments, the magnetic particles comprise metal chalcogenides.Suitable metal chalcogenides comprise magnetic particles comprising anycombination of element or ionic form thereof M selected from at leastone of Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta,Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn,Cd, Hg, B, Al, Ga, In, TI, Si, Ge, Sn, Pb, As, Sb, Bi, or theircombinations, in combination with elements or elemental form of at leastone of O, S, Se, or Te. In some embodiments, the crystallisationfacilitators comprise metal chalcogenide having the formulaM_(x)N_(y)C_(z), where M,N are selected from at least one of Li, Na, K,Rb, Be, Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re,Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, B, Al, Ga,In, TI, Si, Ge, Sn, Pb, As, Sb, Bi, C is selected from at least one ofO, S, Se, Te, x is any number from 0 to 10, y is any number from 0 to 10and z is any number from 0 to 10. The metal chalcogenide particles mayin some embodiments have a core-shell structure in which the corecomprises at least one metal chalcogenide as previously described andthe shell comprises at least one metal chalcogenide as previouslydescribed. In some forms, the core-shell structure may include multipleshells. In embodiments, the magnetic particles comprise at least one ofMgFe₂O₄, Fe₃O₄, C-coated Co, CoFe₂O₄, NiFe₂O₄,Pyridine-2,6-diamine-functionalized SiO₂, orPyridine-2,6-diamine-functionalized Fe₃O₄.

The advantages of these magnetic materials are:

-   -   Local heat generation—i.e. heat can be generated insitu the        material by applying an AC magnetic field (as discussed        previously) as opposed to using an external heating source;    -   Fast heating of material, due to local heat generation avoiding        thermal and energy loss through thermal heating of surrounding        materials; and    -   High energy conversion efficiency

The combination of the magnetic particles with MOFs to form a magneticframework composite material yields an adsorbent with exceptionaladsorption behaviour as a result of the MOFs and high efficiency ofinduction heating as a result of the magnetic particles.

EXAMPLES

The following examples use AlFu as the water adsorbent MOF in themagnetic framework composite material. It should be appreciated that themagnetic framework composite material could use any number of otherwater adsorbent MOFs through direct substitution of that MOF within themagnetic framework composite material pellets.

Example 1—Magnetic Induction Swing Water Harvesting 1. MagneticFramework Composite Material

The synthesis of AlFu and the preparation of shaped water adsorbentcomposite bodies comprising AlFu magnetic framework composite material(MFC), hereafter referred to as MFC pellets, are described. The examplesdemonstrate that the experimental system can produce water repeatedly,with 1.2 grams of water having been produced from roughly 3 cycles ofthe described method and system. Cycle times were approximately 30minutes in duration. In the examples outlined below, 0.4 g of water wascaptured using 5 g of the inventive shaped composite material within 28minutes. This provides the following production and energy use:

-   -   Anticipated water production capacity: 4.3 L/kg of MOF a day        with a cycle time of 28 mins; and    -   Anticipated energy use: 12 kWh/L.

As a comparison, the system described in Yaghi 1 and Yaghi 2 (referredto in the Background of the Invention section) uses sunlight as energysource for regeneration of the MOF. This device was reported as beingcapable of capturing 2.8 litres of water per kilogram of MOF daily atrelative humidity levels as low as 20% at 35° C. in Yaghi 1. Yaghi 2indicates that about 0.75 g of water was produced from 3 g of MOF within16.5 hours in the same conditions. This equates to an anticipated waterproduction capacity of 0.25 L/kg of MOF daily. The process of thepresent invention therefore has a significantly higher water productionrate than the system taught in Yaghi.

The inventors note that Yaghi 1 originally claimed that their device wascapable of capturing 2.8 litres of water per kilogram of MOF daily atrelative humidity levels as low as 20% at 35° C. However, this higherproduction rate appears to have been greatly overestimated in thatpaper, as further experimental work published in Yaghi 2 using the sameset up reports a production rate being an order of magnitude lower at0.25 litres of water per kilogram of MOF daily at 20% RH and 35° C.Inventors consider that the production rate published in Yaghi 2reflects the actual production rate of this MOF-801 based system.

1.1 Preparation of Magnetic Framework Composites

The synthesis of aluminium fumarate MOF and the preparation of aluminiumfumarate MFC pellets are described.

1.1.1 Aluminium Fumarate Synthesis

Within this work, two different scaled batches of aluminium fumaratewere synthesized. For the evaluation of different contents of magneticnanoparticles on moisture adsorption and induction heating performanceof the composite material a smaller batch, designated Batch I, wasprepared. While for experiments with the water capture rig 600 (see FIG.6 ), a larger batch, designated Batch II, was synthesized.

The experimental setup 400 of the aluminium fumarate synthesis reactionis presented in FIG. 2A.

The two precursor solutions named A and B were synthesized as follows:

For solution A, aluminium sulfate octadecahydrate was dissolved indeionized water using a magnetic stirrer 406. Precursor solution B wasprepared by dissolving sodium hydroxide pellets and fumaric acid with apurity of 99% in deionized water under stirring with a magnetic stirrer(not shown). The composition of both solutions can be taken from Table1.

TABLE 1 Composition of precursor solutions for aluminium fumaratesynthesis Precursor Solution A Precursor Solution B Aluminium DeionizedSodium Fumaric Deionized Sulfate Water Hydroxide Acid Water Batch I 35 g  150 ml 13.35 g  12.9 g   191 ml Batch II 90 g 385.7 ml 34.33 g 33.17 g491.1 ml

Solution B was then filled into a round bottom flask 410 and heated upto 60° C. using a heating mantel 408. A mechanical stirrer 402 was usedto stir the liquid. When 60° C. were reached, precursor solution A wasadded. The mixture was then stirred for 20 minutes at 60° C. measuredusing temperature transducer 404.

Afterwards, the suspension was filled into centrifuge tubes (not shown)and centrifuged for 8 to 10 minutes at 6000 rpm for Batch I and 4500 rpmfor Batch II, respectively. The liquid was then removed from thesedimented MOF crystals. After that aluminium fumarate was washed usingthe following procedure. At first, deionized water was added to the MOFcrystals. The suspension was then shaken by hand until the sedimentswere homogenously mixed up. Furthermore, the suspension was mixed for 15minutes onto a roller mixer for Batch I and an orbital shaker for BatchII, respectively. Afterwards, the suspension was centrifuged using thesame settings as mentioned before. After removing the liquid, thewashing procedure with deionized water was repeated for another threetimes.

Subsequently, aluminium fumarate was washed with methanol for one timefollowing the same procedure as described before. Aluminium fumarateafter the washing procedure is shown in FIG. 2B.

After the washing steps, the MOF crystals were pre-dried overnight in aglove bag under nitrogen atmosphere. Afterwards, the MOF was driedovernight in an oven at 100° C. under nitrogen atmosphere. Subsequently,the temperature was increased to 130° C. and the oven was evacuated toactivate the MOF for 6 to 8 hours.

1.1.2 Aluminium Fumarate Composite-Pellet Preparation

A smooth paste needs to be prepared for the extrusion of MOF pellets.Therefore, the MOF was ground using a mortar and a pastel (notillustrated) for the smaller Batch I and a coffee grinder (notillustrated) for the larger Batch II, respectively. After grinding, theMOF was sieved through a 212 μm sieve. In case of Batch II, thealuminium fumarate powder was sieved through a 150 μm sieve. The MOFpowder was then weighed into a jar. Afterwards, magnetic nanoparticles(MNPs) were added. In this work, magnesium ferrite was chosen asmagnetic nanoparticles. However, it should be appreciated that othermagnetic nanoparticles could equally be used. The powder mixture wasthen shook by hand for about 10 minutes until the colour of the powderwas homogenously brownish. Afterwards, the powder was filled into a bowland a hydrophilic binder (hydroxypropyl cellulose (HPC)) was added. Toinvestigate the effect of the amount of magnetic nanoparticles on wateruptake and magnetic induction heating, different composites wereprepared. The composition of the prepared samples is provided in Table2.

TABLE 2 Composition of different aluminium fumarate composite samplesConcentration of Magnesium Ferrite Concentration of Batch [wt %] Binder[wt %] Batch I 0 0 0 1 1 1 3 1 5 1 Batch II 3 1

Furthermore, a solvent, in this case deionised water was added to makethe mixture pastier. In case of Batch I, also small amounts of ethanolwere added. The components were then well mixed until an ice cream likepaste has formed.

For the extrusion of composites made from Batch I, a syringe with around nozzle was used (not illustrated). In case of Batch II, a handextruder 500 with a triangular shaped nozzle 505 was chosen. Theextruder is illustrated in FIG. 3A. The triangular shaped extrusionattachment 505 was chosen in order to increase the packing density ofthe produced pellets as explained previously. Furthermore, magnesiumstearate was used as lubricant for preparation of pellets from Batch II.The magnesium stearate powder was greased onto the inner walls of thehand extruder 500. The paste was extruded onto filter paper and driedfor at least 10 minutes. Afterwards, the extruded MOF was cut into 3 to5 mm long pellets using a razor blade.

The pellets were then dried in an oven at 100° C. under vacuum (reducedpressure of less than 100 mbar) for 24 hours. The different MOFcomposite pellets (Aluminium fumarate and aluminium fumarate compositepellets) are presented in FIG. 4 which show (A) Pristine MOF; (B) 1 wt %binder; (C) 1 wt % MNP; (D) 3 wt % MNP; and (E) 5 wt % MNP. A schematicof this overall process is shown in FIG. 3B.

1.2 Analysis of Aluminium Fumarate Composites

The first part of this section deals with different analysis methodsthat have been used to characterize the structure of aluminium fumaratecomposites. Furthermore, methods that evaluate the performance of thecomposites regarding water uptake and magnetic induction heating aredescribed.

1.2.1 X-Ray Diffraction

All samples have been characterized using powder X-ray diffraction(PXRD) as well as small-angle X-ray scattering (SAXS) and wide-angleX-ray scattering (WAXS). For X-ray diffraction analysis, the pelletswere ground first to fill them into the sample holder.

Powder X-ray diffraction was performed employing a Bruker D8 AdvanceX-ray Diffractometer operating under CuKα radiation. The diffractometerwas equipped with a Lynx Eye detector. All samples were scanned over the28 range 5° to 105° with a step size of 0.02° and a count time of 1.6seconds per step. To give an equivalent time of 284.8 seconds per step,178/192 of the sensor strips on the Lynx Eye were used. The Bruker XRDsearch match program EVA™4.2 was used to perform analyses on thecollected PXRD data.

Aluminium Fumarate is not present in the JCPDS database. Therefore, forreference a simulation of the structure of aluminium fumarate wasgenerated in TOPAS using a simplified model for the geometry of thementioned diffractometer.

Small- and wide-angle X-ray scattering was performed at the AustralianSynchrotron. The samples were mounted onto sample holder plates. Allsamples despite of magnesium ferrite control samples were analysed with1% Flux and an exposure time of 1 sec. Magnesium ferrite samples wereanalysed at 100% Flux.

1.2.2 Infrared Spectroscopy

Infrared spectra analysis was performed using a Thermo ScientificNicolet 6700 FT-IR spectrometer. The samples were analysed in thewavenumber range from 500 to 4000 cm⁻¹.

1.2.3 Scanning Electron Microscope Imaging

Specimens for scanning electron microscope (SEM) imaging were preparedby diluting the samples in water and then trickling the suspension ontoa silicon waver. The silicon waver was then stuck onto a SEM specimenstub using carbon tape. Before scanning, the samples were coated withiridium to increase the signal to noise ration during microscopy. TheSEM images were taken using a Carl Zeiss Gemini SEM 450 instrument at10000 times magnification.

1.2.4 Surface Area and Porosity Measurements

Surface area and porosity measurements of aluminium fumarate compositeswere analysed using a Micrometrics ASAP 2420 high throughput analysissystem.

At first, composite pellets were filled into pre-weighed analysis tubesand capped with Transeal caps. The samples were then degassed for 24hours at 140° C. under vacuum. Afterwards, the tubes with the containingdegassed samples were weighed to determine the mass of the driedpellets. The tubes were then transferred to the analysis ports of theinstrument. Langmuir and Brunauer-Emmett-Teller (BET) surface areas aswell as pore size distribution of all samples were determined bycollecting nitrogen isotherms at 77K in a liquid nitrogen bath. Poresize distribution was determined using density functional theory (DFT).

The BET surface area of samples made from batch I was measured threetimes in order to determine the variation within the analysis. Theaveraged surface area x was calculated using Equation 1.1:

$\begin{matrix}{\overset{\_}{x} = {\frac{1}{n}{\sum\limits_{i}^{n}x_{i}}}} & (1.1)\end{matrix}$

Where n is the total number of experiments and xi is the surface area ofthe experiment i.

Furthermore, the standard deviation s_(n) was calculated. This was doneby using Equation 1.2.

$\begin{matrix}{s_{n} = \sqrt{\frac{1}{n}{\sum\limits_{i}^{n}( {\overset{\_}{x} - x_{i}} )^{2}}}} & (1.2)\end{matrix}$1.2.5 Water Uptake Capacity Determination

Water Uptake capacity was measured using a Quantachrome InstrumentsAutosorb-1 analyser.

The samples were filled into pre-weighed analysis tubes. After that, thematerial was degassed for 16 hours at 140° C. under vacuum. Afterwards,the weight of the dried pellets was determined. The tubes were thenconnected to the analysis port for water vapour adsorption measurement.In order to ensure a constant temperature during the analysis, thesample tubes were put into a water bath at room temperature. Watervapour uptake was measured using pure water vapour at relative pressuresp/p₀ from 0.1 to 0.5 with a step size of 0.1. The water vapouradsorption experiments have only been performed once because it takesalmost one week to run a single isotherm.

1.2.6 Investigation of Magnetic Induction Heating

To evaluate magnetic induction heating of magnetic framework composites,heating rate and efficiency of induction heating have been investigated.

For the induction heating experiments an Ambrell Easy Heat 1.2 kWinduction unit was used. The induction coil 560 that was attached to thework head is made from copper. It had three turns, an inner diameter of4 cm and a length of 2.5 cm. A water chiller 562 was used to cool downthe coil 560 during the experiment.

The setup 550 for the induction heating and efficiency experiments isshown in FIG. 5 . A certain amount of the sample was filled into a glassvial 565. To monitor the temperature increase of the sample over timeduring induction heating a fibre optic cable sensor 566 was introducedinto the centre of the bed 567. The sensor 566 was connected to anOpSens FOTS100 temperature data logger 570. The glass vial 565 was putinto the centre of the coil 560 so that the middle of the bed's heightwas in line with the middle of the coil's height.

To monitor the energy that is consumed by the induction heating unitduring the experiment a Cabac Power-Mate™ power meter 575 was used. Thepower that is needed to heat up the sample was calculated as following.

At first, the coil was operated without any sample in the magnetic fieldto get a baseline. Therefore, the energy was measured for 5 minutes. Thepower was then calculated using Equation 1.3.

$\begin{matrix}{{{Power}{consumed}} = \frac{{Energy}{consumed}{over}5{{minutes}\lbrack{kWh}\rbrack}}{{Time}{( {5{minutes}} )\lbrack h\rbrack}}} & (1.3)\end{matrix}$

During heating of the sample, energy was also measured for the first 5minutes of induction heating. The power was then calculated the same wayas mentioned before.

For investigating the heating effect of magnetic framework compositesexposed to an external magnetic field, temperature of the sample wasmeasured over time for different composites and for different amounts ofthe composite pellets. All experiments were performed for more than 20minutes. After this time the heating curve for induction heating wasconstant for all samples.

The initial heating rate was used to quantify the induction heatingeffect. This rate was determined by calculating the linear slope of thetemperature profile (dT/dt)t=0 at the beginning of the experiment. Theheating curve is therefore approximated by Equation 1.4:

$\begin{matrix}{{T(t)} = {T_{0} + {\Delta{T_{\max}\lbrack {1 - e^{\frac{t}{T}}} \rbrack}}}} & (1.4)\end{matrix}$

Where T₀ is the initial temperature of the pellets, ΔT_(max) is thesaturation temperature increase (T_(max)−T₀) and T is the time constantof heating which corresponds to the time when the temperature reachesapproximately 63% of ΔT_(max).

Efficiency of induction heating of magnetic framework composites wasquantified using Equation 1.5.

$\begin{matrix}{{{Efficiency}\%} = {\frac{P_{Coil}}{P_{SAR}} \times 100\%}} & (1.5)\end{matrix}$

In this equation, P_(Coil) is the power that is consumed by the coilduring induction heating and it is calculated by using Equation 1.6.P _(Coil) =P _(consumed,heating MFC) −P_(consumed, without MFC in field)  (1.6)

The specific adsorption rate (SAR) is usually used to estimate theheating effect of magnetic nanoparticles exposed to an external magneticfield. The SAR was determined by dispersing 10 mg of magneticnanoparticles in 100 ml of deionized water. The suspension was then putinto the centre of the induction coil and triggered with a magneticfield. The temperature increase of the suspension was measured using anoptic fibre cable and a temperature data logger. The specific adsorptionrate can then be calculated using Equation 1.7.

$\begin{matrix}{{SAR} = {C_{water} \times \frac{m_{water}}{m_{nanoparticles}} \times ( \frac{dT}{dt} )_{t = 0}}} & (1.7)\end{matrix}$

In this equation, C_(water) is the specific heat capacity of water,m_(water) is the mass of water, m_(nanoparticles) is the mass ofmagnetic nanoparticles in the suspension and (dT/dt)t=0 is the initialheating rate. The initial gradient of the heating curve was calculatedas mentioned before.

Finally, the power that is generated by the magnetic nanoparticles inthe composite PSAR can then be calculated using Equation 1.8.P _(SAR)=SAR×Magnetic nanoparticle content of MFC pellet (g)  (1.8)

All experiments for determination of the initial heating rate andefficiency of induction heating were carried out for three times todetermine a standard variation.

1.3 Proof of Concept Experiments for Magnetic Induction Vacuum SwingAdsorption

This subsection deals with different methods that have been used toevaluate the performance of a magnetic induction vacuum swing adsorptionprocess for water capture from ambient air. These experiments werecarried out with a self-constructed water capturing rig on bench scale.The schematic process flow diagram of the Water capturing rig 700 isprovided in FIG. 6 .

Moisturized nitrogen was used as test gas for water capture andbreakthrough experiments. A nitrogen stream from gas supply 702 at 1 barwas split up into a dry gas stream 704 and a wet gas stream 706 that wasmoisturized by bubbling it through deionized water in bubbler 708. Flowof each stream were measured using flowmeters 710 and 711. The desiredhumidity of the feed stream for the adsorption column was reached bysetting the ratio of the dry gas stream 704 and the wet gas stream 706.

A vertically orientated adsorption column 720 was used comprising a 1inch polyether ether ketone tube. A perforated Teflon spacer was gluedin the bottom part of the tube to hold the adsorption bed thereon withinthe tube (not illustrated but enclosed within adsorption column 720).Furthermore, glass wool was used to prevent pellets from falling throughthe holes of the spacer. The tube was connected to the feed and outletpipes using stainless steel ultra-Torr vacuum fittings purchased fromSwagelok.

In these experiments an Ambrell EasyHeat 3542 LI induction coil 725 witha system power of 4.2 kW was used. A copper coil with 5 turns, an innerdiameter of 4 cm and a length of 5 cm was connected to the work head ofthe induction coil 725. The feed and outlet pressure were monitoredusing manometers 730. To measure the temperature in the adsorption bed,a fibre optic cable 732 was introduced into the middle of the packed bedand connected to a temperature data logger. A RS 1365 Data loggingHumidity-Temperature Meter 735 was used to monitor the humidity of theoutlet stream 745 of the adsorption column 720.

For water capture, the out-coming stream 645 was lead through a coldtrap 740 containing dry ice to condensate the moisture to produce water755. A vacuum pump 750 was used to generate the driving force for thedesorbed gas stream 745.

1.3.1 Water Collection Experiments

For water collection experiments, aluminium fumarate magnetic frameworkcomposite pellets made from batch I containing 3 wt % magneticnanoparticles were filled into the adsorption column. In order toincrease the packing density, the pipe was tapped onto the bench for afew times.

A dry nitrogen stream with different volume flow rates was flown throughthe packed adsorption column in order to determine the back pressure asa function of the flow rate.

The determined back pressure was then used to calculate the desiredrelative humidity of the feed stream. For the desired humidity, desertlike conditions were chosen. The relative humidity in these areas isabout 35% at 35° C. and atmospheric pressure. To simplify theexperimental set up, the water uptake experiments in this work werecarried out at room temperature. This simplification is justifiedbecause the temperature dependence of water vapour uptake on aluminiumfumarate in this temperature region is negligible. However, in order toget comparable results, calculations of humidity were based on watercontent in the desert like air. The dessert like conditions correspondto a water content of 11273 ppmV in a pure nitrogen atmosphere(calculated with Michel Instruments HumidityCalculator—http://www.michell.com/us/calculator/).

Based on this water content, the ratio of the dry and the moisturizedgas stream can then be calculated.

For water capturing experiments, MFC pellets were activated bytriggering them with an alternating current magnetic field and directinga flow of dry nitrogen stream through the column. Activation of thematerial was performed until the humidity of the out coming gas streamwas zero. It is noted that this activation step was used forexperimental date collection purposes only in order to obtain a dry MOFfor measurement accuracy. A commercial system would not generallyrequire this activation/drying step to be performed as any preadsorbedmoisture in the MOF material in the system would simply be desorbed inthe first cycle of operation of the system.

Before charging the MFC pellets with water vapour, volume flow rates ofthe dry and the moisturized streams were set. The resulting feed streamwas first vented to allow the humidification of the gas stream tostabilize. After three minutes, the valve in front of the adsorptioncolumn was switched to enable the feed to flow through the column.

During moisture adsorption, the humidity of the outlet stream of thecolumn was measured and noted down every 30 seconds in order todetermine breakthrough curves. After the humidity of the vented streamhad stabilized, the feed stream was turned off and the valve was closedtowards the column.

For regeneration, in a first experiment only humidity was measuredduring desorption in order to determine the duration of the regenerationstep. Therefore, during induction heating, a dry nitrogen stream waslead through the adsorption bed to flush the column.

In order to determine breakthrough curves, the relative humidity thatwas measured in the outlet stream of the column has been normalized.Therefore, the measured humidity was divided by the humidity of the outcoming stream that is reached when the adsorption bed is saturated.

2. Results and Discussion

In this section, results of characterisation and performance analysis ofaluminium fumarate composites and its ability for capturing water fromambient air using a magnetic induction vacuum swing adsorption processare presented and discussed.

2.1. Structural Characterisation of Composite Material

The PXRD pattern of aluminium fumarate and aluminium fumarate with 1 wt% of binder is presented in FIG. 7 . Furthermore, a simulated pattern ofaluminium fumarate is plotted. It can be seen that most of the peaks inthe trace of the pristine MOF and the MOF with 1 wt % binder are areasonable match to the simulated phase.

The PXRD pattern of different aluminium fumarate magnetic frameworkcomposites made from Batch I can be taken from FIG. 8 . Furthermore, thetrace of magnesium ferrite is plotted as reference.

The traces of all composites match the PXRD pattern of aluminiumfumarate containing only the binder.

For the composite containing 1 wt % of magnetic nanoparticles, the PXRDpattern does not reveal a significant evidence of magnesium ferrite inthe sample. Presumably, any magnetic nanoparticles present in thissample are below the detection limit.

The PXRD pattern of composites with 3 wt % and 5 wt % of magnesiumferrite look fairly similar with a trace of magnetic nanoparticles beingvisible at the 2θ angle 35°.

The PXRD trace of the magnetic framework composite made from Batch IIare presented in FIG. 9 . The pattern matches the trace of the pristineMOF of this batch. Similar to the composites made from Batch I, there isa trace of magnesium ferrite visible at the 2θ angle 35°.

The surface morphology of aluminium fumarate has been studied usingscanning electron microscopy and is presented in FIG. 10 . It can beobserved from this Figure that this MOF has a quite rough surface and apoorly crystalline structure.

The narrow particle size distribution of magnesium ferrite nanoparticlesare presented in FIG. 11 . The average particle size of this sample isabout 150 nm.

The incorporation of aluminium fumarate and magnesium ferritenanoparticles can be observed from FIG. 12 . The circled sections markedwith A indicate examples of the location of magnesium ferritenanoparticles in the composite. It can be seen, that the nanoparticlesare fairly equally distributed within the MOF structure.

The average BET surface area of aluminium fumarate magnetic frameworkcomposites as a function of magnetic nanoparticle loading is shown inFIG. 13 . The sample containing no magnesium ferrite refers to compositepellets that were made only from the MOF and binder. The average surfacearea of pristine aluminium fumarate pellets is 976 m²/g. The standarddeviation of the measurements for this sample is 33 m²/g.

From the plot and the surface area of the pristine MOF it can be taken,that there is not a significant change in the BET surface area foradding the binder and for an increasing magnetic nanoparticleconcentration. Even though there is a slight decrease in surface areavisible for higher nanoparticle loadings, the average surface area isstill in the same order of magnitude. Furthermore, the standarddeviation for the different experiments does not substantiate thedecreasing trend.

The BET surface area of the second batch and composite pellets preparedfrom this batch is shown in Table 3. It can be seen that there is alsonot a significant difference in the surface area between the pristineMOF and its composite. However, the surface area of MOF pellets frombatch II is lower that on pellets prepared from the first batch.

TABLE 3 BET surface area of aluminium fumarate batch II and aluminiumfumarate batch II composite Concentration MNPs BET Surface Area Sample[wt %] [m²/g] Pristine MOF 0 876 Composite 3 849

The pore size distribution of aluminium fumarate pellets are presentedin FIG. 14 . The main pores size distribution is in the microporous areawhich is below 2 nm. The microporosity of this sample can also beconfirmed with the nitrogen adsorption-desorption isotherm which isshown in FIG. 15 . According to IUPAC classification of adsorptionisotherms, the shape of this isotherm corresponds to a physisorptionisotherm type H4. This shape is typical for microporous materials wherethe high uptake at low relative pressures is associated with the fillingof micropores.

FIG. 16 illustrates that most of the pores of aluminium fumaratecomposite pellets are also present in the microporous are below 2 nm.Only for the sample containing 3 wt % of magnesium ferritenanoparticles, there are pores in the mesoporous area between 2 nm and50 nm.

2.2 Performance Analysis of Aluminium Fumarate Composites

In this subsection, water uptake results and magnetic induction heatingperformance of the prepared material are presented and discussed.Furthermore, the results of induction heating experiments are comparedto a conventional heating method.

2.2.1 Water Uptake Performance

The water vapour adsorption isotherms of samples prepared for prestudies on the effect of an increasing amount of nanoparticles in theMOF can be taken from FIG. 17 . All isotherms were collected at roomtemperature. The plots show that there is not a significant differencebetween the moisture uptake capacities for the different composites.This was already shown with nitrogen isotherms in section 2.1. In orderto check the accuracy of the measurements, the isotherm of the compositecontaining 5 wt % magnesium ferrite was collected two times. The Figureshows that the values of the second measurement vary by approx. 70% fromthe first measurement. Regarding this accuracy, it can be confirmed thatmoisture uptake of the composite pellets does not differ strongly fromvapour uptake from pristine aluminium fumarate pellets.

The water vapour isotherms of aluminium fumarate and aluminium fumaratecomposite pellets prepared from the larger batch are presented in FIG.18 . Regarding the experimental variance of moisture adsorptionexperiments, it can be indicated that the water vapour uptake of thecomposite does not significantly differ to the one of the pristine MOF.

2.2.2 Induction Heating Performance and Comparison to a ConventionalHeating Method

The induction heating performance was evaluated, using the initialheating rate. The initial heating rate was determined as described inSection 1.2.6. Results of these experiments are shown in FIG. 19 . Thefield strength in these experiments was 12.6 mT. It can be seen, thatthe initial heating rate increases with the concentration of magneticnanoparticles incorporated into the metal organic framework.Furthermore, the heating rate increases fairly linear with the amount ofsample that is triggered by the alternating current magnetic field.

In addition to the initial heating rate, the energy conversionefficiency of induction heating of the prepared composites is shown inFIG. 20 . The field strength was 12.6 mT. Similar to the initial heatingrate, the efficiency also increases with an increase in magneticnanoparticle loading and an increase in sample weight. The increase inefficiency with an increasing sample mass is counterintuitive as onewould know from conventional heating methods. However, with anincreasing amount of magnetic framework composite pellets, the amount ofmagnetic nanoparticles triggered by the magnetic field also increases.Therefore, the coupling between the nanoparticles is improved.

For applications on industrial scale, where much larger amounts of MFCpellets are used, the energy conversion efficiency is expected to beeven higher than shown in this experiment. That is because of a loss ofheat that is caused by non-existent insulation of the heated sample. Theloss is not considered in the calculation of the SAR value. To minimizethis heat loss, an adiabatic experimental set up needs to be used.However, the non-adiabatic system delivers quick and reliable SAR valueswithout the need for extensive, time-consuming and expensive adiabaticmeasurements.

In addition to that, the efficiency could be further improved byutilizing induction heating systems that are not water cooled. Watercooled systems require separate support systems with pumps andconnections that increase complexity and costs of the system. Inductionheating systems that do not need direct cooling have been reported toachieve up to 90% energy efficiency.

2.3 Proof of Concept: Magnetic Induction Vacuum Swing Adsorption

The normalized humidity in the outlet stream of the column duringadsorption of moisture is presented in FIG. 21 . For this experiment,the relative humidity in the feed stream was set to 50% at a surroundingtemperature of 22° C. This corresponds to the same moistureconcentration that is present in the driest areas of the world. Thevolume flow rate for the moisturized and the dry nitrogen stream wereboth set to 4 SLPM. With these settings, the adsorption bed is fullysaturated after approximately one hour. After about 17 minutes thehumidity of the out coming stream stabilizes for approx. 8 minutes. Thismight be due to a sectional higher packing density along the columnlength which is caused by the inhomogeneity of the pellet length.

In order to reduce the cycle time, for further experiments thebreakthrough point where adsorption is stopped was set to the time when90% of the maximum outlet humidity is reached. This is after approx. 27minutes.

The temperature that was measured during adsorption of water vapour isshown in FIG. 22 . The temperature increases in the beginning due to thereleased heat of adsorption.

The normalized humidity during regeneration is shown in FIG. 23 . Due tothe height of the adsorption bed, the induction coil needed to be placedat two different positions in order to heat up the whole material.First, the coil was placed at the upper part of the column. Afterapprox. 2 minutes, the humidity increases drastically due to the rapidheating rate of magnetic induced heating. Almost 20 minutes later, thehumidity of the out coming stream decreases as the water amount capturedin the MOF also decreases. Right before the humidity in the outletstream settles, the coil was moved to the lower part. The water that isstill adsorbed on the material in the lower part of the column istherefore released. The power of the induction coil was shut off whenthe humidity reached zero.

The temperature over time during regeneration of water vapour can betaken from FIG. 24 . It can be seen from that Figure and the plot of thenormalized humidity during regeneration that as soon as the temperaturereaches about 50° C., water release starts. The temperature decreases asthe coil was moved to the lower part of the column. That is because thetemperature sensor sits above the middle of the adsorption bed.

Based on the adsorption isotherms for moisture and the pre studies onthe behaviour of the column regarding water adsorption and regeneration,a theoretical yield for the rig can be calculated.

In order to evaluate the energy consumption and efficiency of a magneticinduction vacuum swing adsorption process, energy was measured duringregeneration of the MOF composite. For these measurements the 1.2 kWinduction heating system was chosen. The parameters for energyefficiency experiments can be taken from Table 4. The energy consumptionwas monitored using an energy data logger.

TABLE 4 Parameter energy consumption measurements Parameter Value UnitMass MFC pellet 5 g Flow rate dry N₂ stream 4 SLPM Flow rate wet N₂stream 4 SLPM Surrounding temperature 22 °C. Current induction heatingsystem 225.6 A Frequency induction heating system 268 kHz

Before the actual experiment a breakthrough curve for the set updescribed in Table 4 was determined. Therefore, the activated MOFcomposite pellets were charged with water vapour for twenty minutes.After this time the adsorption bed was fully loaded with moisture. Thebreakthrough curve is presented in FIG. 21 .

However, in order to increase the overall efficiency of the process, thebreakthrough point where adsorption is stopped for the experiments waschosen to be when 90% of the maximum outlet humidity was reached.

After adsorption of water vapour, the regeneration was started andenergy consumption of the induction heating system was monitored.Regeneration of the adsorption bed was performed for twenty minutes.This experiment was repeated three times. The results can be taken fromTable 5. In this table, the cycle time is the total time for adsorptionand regeneration. The capture efficiency is calculated as the ratiobetween the amount of moisture that is fed into the column and theamount of water that is captured by the absorbance. The calculated priceper litre shows there are reasonable prices for water captured from airusing this methodology.

TABLE 5 Results water capture experiments Yield Energy Energy PriceCycle [L Capture Con- Conversion per Cycle Time kg⁻¹ Efficiency sumptionEfficiency Litre* No [min] day⁻¹] [%] [kWh/L] [%] [$/L] 1 28 4.1 57.312.8 98.3 3.5 2 28 4.6 64.4 10.4 106.7 2.9 3 28 4.1 57.3 13.0 96.4 3.6*Excluding capital costs

3. Water Analysis

An IPC analysis was conducted on a comparative Milli-Q water sample anda Milli-Q water sample mixed with water captured using the inventivemethod from cycle 1 (Table 5) in with a dilution ratio of 1:15 ofinventive water to Milli-Q. Water collected from cycle 1 was analysed totest the water for its suitability as potable water. The sample wasdiluted with ultrapure water with a dilution rate of 1:15. The watersample was analysed for cations (Ca⁺, K⁺, Mg⁺, Na⁺, S⁺) and metals (Al,As, B, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, P, Pb, Sb, Se, Si, Sr, Zn) usinginductively coupled plasma mass spectrometry. Additionally, ionchromatography was performed to analyse the water for anions (F⁻, Cl⁻,Br⁻, NO₃ ⁻, SO₄ ⁻).

IPC analysis of both samples followed testing standards as follows:

-   -   Fluoride, bromide, sulfate [APHA method 4110]. These common        anions are determined by ion chromatography using a Dionex        ICS-2500 system with 2 mm AS19 anion separation column and        potassium hydroxide eluent generated on line, followed by        conductivity detection after chemical suppression. With a flow        rate of 0.25 mL per minute the anions F⁻, Cl⁻, Br⁻, NO₃ ⁻ and        SO₄ ²⁻ are eluted between 3.5 and 25 minutes. Each ion        concentration is calculated from peak areas using a 25 μL        injection and compared to calibration graphs generated from a        set of mixed standards with a range of concentrations.    -   Cations and metals [APHA method 3120]. A range of elements are        determined by Inductively Coupled Plasma Optical Emission        Spectroscopy (ICPOES). The sample is nebulised into the plasma        of an Agilent 5100 ICPOES. The emission spectra of the elements        of interest are measured simultaneously. This determines the        major cations (Ca, K, Mg and Na) along with trace elements (Al,        B, Cu, Fe, Mn, Sr and Zn) and the non-metallic elements P, S and        Si.

The results of the IPC analysis are provided in Tables 6A and 6B.

TABLE 6A Results of IPC Analysis of water samples part 1 |----IonChromatography---| ICP Majors F^(—) Cl^(—) Br^(—) NO₃ ^(—) SO₄ ^(═) Ca KMg Na S Sample # mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L 1MIlli-Q <0.05 <0.05 <0.05 1.6 <0.05 <0.1 <0.2 <0.1 <0.2 <0.2 Water 2Sample + <0.05 <0.05 <0.05 4.1 <0.05 <0.1 <0.2 <0.1 <0.2 <0.2 MIlli-QWater

TABLE 6B Results of IPC Analysis of water samples—part 2 ICP Minors AlAs B Cd Co Cr Cu Fe Mn Mo Ni P Pb Sb Se Si Sr Zn # mg/L mg/L mg/L mg/Lmg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L 1<0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.1 <0.05 <0.05 <0.05 <0.2<0.05 <0.1 <0.05 <0.2 <0.05 <0.05 2 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05<0.05 <0.1 <0.05 <0.05 <0.05 <0.2 <0.05 <0.1 <0.05 <0.2 <0.05 <0.05

The results indicate that sample water produced using the method andapparatus of the present invention have a similar content to Milli-Qwater, i.e. ultrapure water as defined by a number of authorities suchas ISO 3696. Thus, apart from nitrate concentrations (NO₃ ⁻), theconcentration of all compounds in each sample (reference and inventivecycle 1) is below the detection limit.

The only significant difference is the nitrate concentrations (NO₃ ⁻),concentrations. The concentration of nitrate in the water samplecollected from cycle 1 is about 60.8 mg/L. In the “Guidelines fordrinking-water quality” the World Health Organisation (WHO) hasrestricted nitrate concentration in potable water to 50 mg/L. Theconcentration of nitrate in the control/reference ultrapure water sampleis also elevated being 1.6 mg/L. The concentration of NO₃ ⁻ in ultrapurewater type I however should be lower than 0.2 mg/L according to ISO3696. It is thought that the abnormal nitrate concentrations of bothwater samples may be the result of contamination either during samplepreparation or during sample analysis.

Example 2—Binders 4. Comparative Example—Binders

The following provides a comparative example of the water adsorptionproperties of a water adsorption body/pellet formed using a hydrophobicbinder. The inventors have surprisingly found that a hydrophilic bindermust be used to impart optimal water adsorption properties to the shapedwater adsorbent composite bodies. Non-hydrophilic binders such ashydrophobic binders deliriously affect the water adsorption propertiesof the shaped water adsorbent composite bodies compared to pelletsformed using hydrophobic binders.

A study was conducted on the effect on adsorption properties ofAluminium Fumarate pellets using different binders in aluminium fumaratepellet preparation.

Pellets were prepared following the methodology set out in section1.1.2. However, the binder composition was varied between two batches ofpellets. A first batch of pellets was made using the first batch (batchI discussed above) of AlFu (designated Aluminium Fumarate (I)) and acellulose siloxane binder, which is a hydrophobic binder. A second batchof pellets was made using the second batch (batch II discussed above) ofAlFu (designated Aluminium Fumarate (II)) and a hydroxypropyl cellulosebinder, which is a hydrophilic binder. The water uptake capacity of eachbatch of pellets was determined following the methodology hereinoutlined.

The results of the water uptake capacity determination are provided inFIG. 25 . A comparison of each batch to the Water Uptake Capacityisotherm for the comprising Aluminium Fumarate batch—i.e. AluminiumFumarate (I) and Aluminium Fumarate (II) is also shown. It is noted thatthe adsorption isotherms between these batched differed due todifferences in the properties of the formed Aluminium Fumarate MOF.

It is also noted from FIG. 25 that aluminium fumarate has a watercapacity between 0.09 to 0.5 g of water per gram of MOF depending on therelative humidity. The typical heat of adsorption of aluminium fumaratefor water is well known and ranges between 60 and 30 kJ/mol depending onthe ambient humidity

The water vapour uptake isotherms shown in FIG. 25 clearly indicate thatusing cellulose siloxane decreases the performance of the MOF. However,when using hydroxypropyl cellulose as a binder, there is no decrease winmoisture uptake visible.

Example 3—Temperature Swing Water Harvesting 5. Experimental

5.1 Testing Rig

FIG. 26 shows the testing rig 600 for the temperature swing waterharvesting device 350 (as illustrated in FIGS. 1C to 1E), with the waterharvesting device 350, power supplies and measurement equipment. Theillustrated testing rig 600 comprises the previously described apparatus300 (FIGS. 1C and 1D) equipped with the following measurement devices:

-   -   Relative humidity data logger 682 “EL-USB-2-LCD+” (Lascar        Electronics Ltd., Wiltshire (United Kingdom)) to measure        relative humidity and air temperature within the container 630        during adsorption and desorption phase of each water harvesting        cycle (WHC).    -   Power meter 683 “Digital DC Watt Meter” (KickAss®, Australia) to        measure the energy consumption of the peltier device 610 during        each desorption phase.    -   Temperature data logger 684 “TC-08” (Pico Technology Ltd.,        Cambridgeshire (United Kingdom)) to log the temperature data of        all thermocouples 375 during each desorption phase.

A regulated DC power supply 685 (0-16 V, 0-10 A) was used to power thepeltier device 610, and a digital-control power supply (0-30 V, 0-3 A)686 was used to power the fan 670. Furthermore, a laptop 687 was used tocollect the data from the relative humidity data logger 682 and thetemperature data logger 684. A precision bench scale 689 “EK-15KL” (A&DCo. Ltd., Tokyo (Japan)) was also used to weigh the water harvestingdevice 350 before and after each adsorption or desorption cycle. Thedifference was calculated to determine the amount of water adsorbedduring the adsorption phase or desorbed during the desorption phase.

5.2 Water Harvesting Experiments

Each water harvesting cycle was run with the same setup and using thefollowing protocol:

The adsorption phase of the ith water harvesting cycle commences usingan assembled water harvesting device 350 and a desorbed MOF packed bed355. All thermocouples 375 were disconnected from the data logger 684and the power supplies 685, 686 were disconnected from the peltierdevice 310 and the fan 370. The lid 334 of the container 330 was removedand the relative humidity data logger 682 was removed from the container330. The whole water harvesting device 350 was put on a scale 689 todetermine the weight m_(des,i-1) with the desorbed MOF packed bed 355.After the RH data logger 682 was set up (sampling rate: 5 min) andstarted on the laptop 687, the fan 370 was connected to its power supply686 and switched on to start the air flow through the heat sinks 320 andpacked bed 355 and thus commencing the adsorption phase. The fan 370 wasswitched off and disconnected from its power supply 686 after a setadsorption time. The water harvesting device 350 was put on the scale689 again to determine the weight m_(ads,i) with a water adsorbed MOFpacked bed 355. The adsorbed amount of water m_(water,ads) can becalculated using:m _(water,ads) =m _(des,i-1) −m _(ads,i)  (4.1)where i is the number of the present water harvesting cycle and i−1 isthe number of the previous water harvesting cycle. Furthermore, the RHdata logger 682 was synchronised with the laptop 687 and the datacollected during adsorption was saved. The RH data logger 687 wasprepared (sampling rate: 15 s) for the desorption phase.

The thermocouples 375 were connected to their data logger 684, and thepeltier device 310 and the fan 370 were connected to the power supplies685, 686 to start the desorption phase. The RH data logger 682 wasstarted and placed in the container 330. The lid 334 of the container330 was placed over the container body 332 and was sealed in place withelectrical tape. The power supply 685 of the peltier element 310 wasswitched on after starting the temperature data logger 684 on the laptop687. The fan 370 was started either together with the peltier element310 or after the MOF packed bed 355 was heated up to a set temperature,depending on the experiment.

The peltier device 310 and fan 370 were switched off after a setdesorption time. The lid 334 of the container 330 was removed from thecontainer body 332 and the data from both data loggers 682, 684 wassaved on the laptop 687. The energy consumption of the peltier device310 was read off the power meter 683. The energy consumption of the fanW_(Fan) was calculated using:W _(Fan) =I _(Fan) ×U _(Fan) ×t _(run)  (4.2)

where I_(Fan) the operating current of the fan, U_(Fan) is the operatingvoltage is of the fan 370, and t_(run) is the runtime of the fan 370.Condensed water was collected with a syringe (not illustrated) from thebase of the container 330. The water volume was measured and the waterharvesting device 350 was put on the scale 689 after removing the powersupplies 685, 686 and the thermocouples 375 were disconnected. Theweight of the water harvesting device 350 after desorption m_(des,i) wasused to calculate the amount of desorbed water m_(water,des) with:m _(water,des) =m _(ads,i) −m _(des,i)  (4.3)

The water harvesting cycle was now completed and the water harvestingdevice 350 was ready to start the next adsorption phase.

5.3 Performance of Peltier-Heated Water Harvesting Device

The aluminium fumarate pellets were characterised to evaluate theperformance of the water harvesting device. The pellets werecharacterised again after the water harvesting cycles to show theusability of aluminium fumarate pellets for water harvesting purposes.Subsequently, 24 water harvesting cycles were run with the device todetermine optimised operation conditions.

5.3.1 Characterisation of MOF Pellets

The MOF pellets, containing 99 wt % aluminium fumarate and 1 wt %binder, was characterised using FTIR, PXRD, nitrogen sorption isotherms,water sorption isotherms, and calculated BET surface area.

Infrared spectroscopy was used to investigate changes in the aluminiumfumarate due to mixing with binder and solvent during the pelletisationprocess. FIG. 27 shows the FTIR patterns of aluminium fumarate with 1 wt% hydroxypropyl cellulose (HPC) binder. Three extrusion batches weremade to produce 200 g of pellets. Aluminium fumarate for all threebatches was prepared as discussed in Example section 1.1.1. The pelletswere prepared following a similar procedure outlined in Example section1.1.2, though in this case the composition of the pellets was formulatedusing aluminium fumarate with 1 wt % hydroxypropyl cellulose (HPC)binder with no magnetic nanoparticle content.

The first batch of pellets, designated “Pellets_01” were mixed withwater and ethanol as solvents to get the required consistency of thepaste for extrusion. However, this solvent formulation leads to a pastestrand that dried too slowly for desired cutting behaviour in thepelletisation process (as described in section 1.1.2). The subsequentpellet batches, Pellets_02 and Pellets_03, were made with pure ethanolas solvent. This results in a quicker drying of the paste during thepelletisation. Furthermore, as FIG. 27 shows, the use of the differentsolvents results in different FTIR patterns. The pellets made with waterand ethanol showed a stronger peak at wave numbers 3400 cm⁻¹ and 1150cm⁻¹ and a weaker peak at 980 cm⁻¹ compared to the other batches madewith pure ethanol as solvent.

FIG. 27 also compares the FTIR pattern of Pellets_01, Pellets_02 andPellets_03 to pristine aluminium fumarate. The pattern of Pellets_01 wasin good accordance with the pattern of pristine aluminium fumarate withboth showing a strong and wide peak around a wave number of 3400 cm⁻¹.The pristine MOF was not activated prior to the infrared spectroscopy.The pellets made with just ethanol as solvent show a slightly differentFTIR pattern compared to the pristine MOF. The pellets were dried overnight at 100° C. The pristine MOF and the pellets with water and ethanolas solvent exhibit strong peaks at 3400 cm⁻¹ and 1150 cm⁻¹ as well as aweaker peak around 980 cm⁻¹. This difference may be attributable towater adsorbed to the MOF.

A powder X-ray diffraction analysis was run on the samples, to evaluatethe crystallinity of the produced aluminium fumarate pellets. Thepattern was compared to the pristine aluminium fumarate as well as asimulated PXRD pattern. FIG. 28 shows the PXRD patterns. The strongpeaks in the patterns of all three pellet batches indicate thecrystallinity of the material. The three PXRD patterns were verysimilar, confirming that the difference in the FTIR pattern was due tothe adsorbed water in one of the pellet batches. The PXRD pattern of thepellets also matches the pristine MOF well. Similarly, the simulatedpattern matches the other patterns satisfactorily.

Samples from all extrusion batches were analysed with a nitrogen uptakemeasurement, to characterise the aluminium fumarate pellets in regard totheir adsorption characteristics. The BET surface area was determined asa quantitative value to compare the adsorption capability. Table 5.4shows the BET and Langmuir surface areas of all three pellet extrusionbatches and the surface areas of the pristine aluminium fumarate.

TABLE 5.4 BET and Langmuir surface areas calculated from nitrogensorption isotherms of pristine aluminium fumarate and aluminium fumaratepellets. BET surface area Langmuir surface area Sample (m² g⁻¹) (m² g⁻¹)Pristine aluminium fumarate 884 1064 Pellets_01 805 1042 Pellets_02 8171061 Pellets_03 824 1071

The surface areas of the pellets were 9%, 8% and 7% lower forPellets_01, Pellets_02 and Pellets_03, respectively. This is likely aresult of the added binder and the processing with solvents during thepelletisation process. Furthermore, the MOF was packed in a rigid shapeand not in a powder like the pristine aluminium fumarate. The pelletsextruded with a mixture of ethanol and water show a slightly lowersurface area. It was decided that pellet extrusion should use pureethanol as solvent for enhanced pellet quality.

Water isotherms were measured for the batch Pellets_02, to determine thewater uptake capacity of this batch. FIG. 29 shows the water uptakeisotherm of the aluminium fumarate pellets compared to a water uptakeisotherm for pristine aluminium fumarate were reported in the literatureby Teo et al. (2017). Experimental study of isotherms and kinetics foradsorption of water on Aluminium Fumarate. International Journal of Heatand Mass Transfer Volume 114, November 2017, Pages 621-627.

Firstly looking at the experimental isotherm (noting that this isothermonly shows the adsorption phase as desorption was not measured due tothe very long equilibrate phases during the isothermal desorption):Aluminium fumarate pellets follow a type-IV isotherm. A first increaseof water uptake is shown in the relative pressure range of 0:01 to 0:03,followed by a plateau with a lower slope. A second steep increase wasobserved at relative pressures between 0:2 and 0:4, again followed by aplateau region. The water uptake at a relative pressure of 0:4 wasaround 0:3 g_(water)=g_(MOF) and a maximal water uptake of 0:34g_(water)=g_(MOF) was observed at a relative pressure of 0:6.

Now looking at the comparison to the Teo isotherm in FIG. 29 , it can beseen that Teo's reported water uptake isotherms of aluminium fumaratewere of type-IV as well and have the steep increases of water uptake inthe same relative pressure range. The water uptake in low relativepressure ranges was lower in the data of Teo, compared to the pellets ofthis work. In high relative pressure ranges the water uptake reported byTeo was higher compared to the pellets of this work. This might be dueto the rigid pellet form as well as the 1 wt % binder in the aluminiumfumarate pellets. Thus, the isotherm of the pellets show water uptake ing per g of MOF pellets, containing 99 wt % aluminium fumarate.

In conclusion, the produced aluminium fumarate pellets were of highcrystallinity and structure comparable to simulated data of X-raydiffraction analysis. The use of ethanol as solvent during thepelletisation process provided the best surface area results.Furthermore, the produced pellets were of still a good quality inregards to water uptake behaviour with a maximum water uptake of 0:34g/g.

5.3.2 Water Harvesting Experiments

Water harvesting cycles with the water harvesting device were run in thetesting rig. For each cycle, containing an adsorption and a desorptionphase the following date was recorded:

-   -   the relative humidity during adsorption and desorption;    -   the temperature in the MOF bed during desorption;    -   the energy consumption of the peltier device and the fan; and    -   the desorbed amount of water.

Twenty four water harvesting cycles were run with the device. The goalof the experiments was to select a suitable peltier device and determinean optimal temperature range for desorption of the MOF bed. Once thebest peltier device was determined the operating parameters wereoptimised with respect to energy consumption and water yield per day.All experiments were run with ambient air in March 2019 in Melbourne(Clayton), Australia. Table 5.1 shows all water harvesting cycles.

TABLE 5.1 List of all water harvesting cycles with operating parameters(Fan parameter: HF - high flow rate [I = 0:09 A], LF - low flow rate [I= 0:02 A], ‘*’ fan switched on during heating and condensation, in allother experiments the fan was just switched on during condensation).Peltier Heating Condensation Condensation No. device current (A) current(A) time (h) Fan  1  29 W 3.0 3.0 3.0 (incl. heating) —  2  29 W 3.5 3.53.0 (incl. heating) —  3  29 W 4.0 4.0 3.0 (incl. heating) —  4  29 W4.0 4.0 3.0 (incl. heating)  HF*  5  29 W 4.0 4.0 2.0 (incl. heating) — 6  29 W 4,0 4.0 1.5 (incl. heating) —  7  29 W 4.0 4.0 1.0 (incl.heating) —  8 110 W 5.0 4.5 2.0 —  9 110 W 5.5 4.5 2.0 — 10 110 W 6.04.5 2.0 — 11 110 W 6.5 4.5 2.0 — 12 110 W 6.5 6.0 2.0  LF* 13 110 W 6.56.5 2.0 HF 14 110 W 6.5 6.5 . . . 5.5 1.5 LF 15 110 W 6.5 6.5 . . . 6.01.0 LF 16 110 W 6.5 6.5 . . . 6.0 0.5 LF 17 110 W 6.5 6.5 0.083 LF 18110 W 6.5 6.5 . . . 5.5 0.5 LF 19 110 W 6.5 6.5 . . . 5.5 0.5 LF 20 110W 6.5 6.5 . . . 4.0 0.5 LF 21 110 W 6.5 6.5 . . . 5.5 0.5 LF 22 110 W6.5 6.5 . . . 5.5 0.5 LF 23 110 W 6.5 6.0 0.5 LF 24 110 W 6.5 6.5 0.5 LF

The first tested peltier device (Adaptive [53] AP2-162-1420-1118 MaxCurrent 7:8 A) had a maximal temperature difference of 95° C. and amaximal heat flow of 29.3 W. The second tested peltier device (Multicomp[54] MCTE1-12712L-S Max Current of 12:0 A) had a maximal temperaturedifference of 68° C. and a maximal heat flow of 110 W. The testedelectrical currents for the peltier device in water harvesting cycle 1to 3 and 8 to 11 were selected by heating experiments, run prior to thewater harvesting cycles.

The heating experiments were run with the peltier device and an unloadedheat sink to determine the maximal temperatures in the heat sink in thecurrent range of the peltier devices. Based on this data the initiallytested currents with the loaded heat sink were elected. Furtherexperiments were run with currents based on the previous waterharvesting cycles. All experiments were evaluated with respect to thespace time yield (STY) of the present operating parameters and theenergy consumption of the device per kg of harvested water. Table 5.2shows the results of the experiments.

TABLE 5.2 Evaluation of all water harvesting cycles. Cycle times markedwith ‘*’ were calculated with a theoretical adsorption time, calculatedfrom Adsorption_14. Water Water Cycle Specific desorbed collected timeSTY energy No. (g) (mL) (hh:mm) (L kg⁻¹ d⁻¹) (kW h kg⁻¹)  1 9.3 4.120:05 0.025 21.95  2 32.4 17.5 20:20 0.106 7.43  3 44.8 28.1 25:30 0.1705.34  4 11.5 7.9 *5:00 0.192 18.34  5 34.9 21.9 *4:00 0.664 4.67  6 22.512.3  3:30 0.426 5.87  7 13.1 4.9 *3:00 0.198 8.60  8 35.2 29.1 *5:000.705 4.20  9 33.4 27.6  4:42 0.712 4.43 10 32.0 24.5 *4:30 0.660 4.5811 26.9 23.1  4:21 0.664 4.42 12 57.9 51.7 *7:31 0.833 3.06 13 49.2 36.7*5:24 0.824 5.61 14 52.7 42.8 *5:32 0.938 3.37 15 44.8 37.2 *4:31 0.9983.05 16 32.3 26.3 *3:08 1.018 2.75 17 19.1 11.2 *1:37 0.838 3.67 18 17.910.7 *1:51 0.701 3.85 19 8.8 2.9 *1.21 0.260 7.12 20 3.0 0.6 *1:21 0.05417.77 21 10.2 2.8  2:50 0.120 18.67 22 11.3 6.6  2:55 0.274 7.92 23 27.421.6 *3:09 0.833 3.35 24 30.7 25.2  3:04 0.998 3.27

As the reported, desorption temperature of aluminium fumarate was 110°C., the peltier device with the greatest temperature difference wastested in the first place. The device was tested with three differentcurrents in WHC 1 to 3. The temperature in the MOF bed during desorptionwas up to 65° C., 70° C. and 80° C. in WHC 1, 2 and 3, respectively.

With increasing temperature in the MOF bed, the amount of desorbed waterincreases as well. The space time yield in the first three cycles wascalculated with the actual adsorption time prior to the desorptionphase. The adsorption was carried out overnight. Thus, the cycle timeswere around 24 h. The peltier device was switched on for three hours forthe desorption phase in these experiments after the adsorption wascompleted. The water was collected afterwards. The highest STY of 0:170L kg⁻¹ d⁻¹ and lowest specific energy consumption of 5:34 kW h kg⁻¹ weremeasured in WHC 3.

WHC 4 was run with the same current as WHC 3. The influence of the fanduring the desorption phase was tested in this cycle. The fan wasswitched on simultaneously with the peltier device. A high airconvection was created in the container 630. Hence, the MOF bed heats upmore slowly during the desorption phase compared to the third cycle. Asa result the highest temperature in the MOF bed after three hours wasjust 50° C. and the resulting amount of harvested water was 7:9 mL,significantly lower than the 28:1 mL in WHC 3. The maximal dissipatedheat of the 29.3 W peltier device was not sufficient to heat up the MOFbed with a high convection. The subsequent experiments with this devicewere therefore carried out without a fan in the container 630 duringdesorption.

Beginning with WHC 4, the space time yield was calculated with atheoretical adsorption time. To calculate a comparable cycle time forall experiments, the adsorption behaviour was logged for one adsorptionphase. The weight of the device was logged during the adsorption of WHC14. The adsorption starts with a MOF bed temperature of 60° C. to takethe cooling from the previous WHC into account. Thus, a water adsorptioncurve over time was created as shown in FIG. 30 . The adsorption timecould then be calculated from the desorbed amount of water.

In WHC 5 to 7 the runtime of the desorption phase was shortened.Consequently, less water needed to be adsorbed allowing more cycles tobe run per day, increasing the STY. However, the results reveal adecline in the STY with shorter desorption phases. This might be aresult of the fact that a majority of the time was used to heat up theMOF bed to elevated temperatures and that with shorter desorption phasesthe maximal reachable temperature decreases. For example, the maximaltemperature in WHC 7 with just 1 h desorption time was 65° C. Thehighest space time yield of 0:664 L kg⁻¹ d⁻¹ was thus reached with adesorption time of 2 h and a corresponding adsorption time of 2 h.Furthermore, the specific energy consumption per harvested litre ofwater was greater even though the runtime of the peltier device wasshorter as the amount of harvested water was significantly lower.

The peltier device was resultantly changed to the 110 W peltier devicefor the subsequent experiments, which was found to be sufficient to heatthe MOF bed to a temperature a temperature of around 70° C. At 70° C. inWHC 3, 82% of the adsorbed water is desorbed after 3 h. Again the firstexperiments were run with different currents of the peltier devicebetween 5:0 A and 6:5 A. The MOF bed was heated up with this current. Assoon as the MOF bed reached a temperature of 68° C. the current waslowered to maintain the temperature. A new time parameter designated‘condensation time’ was used which correlated to the time after whichthe MOF bed had reached the temperature of 68° C. The current tomaintain the temperature during the condensation time was set to 4:5 Ain WHC 8 to 11, based on the data from the heating experiments.

As expected, the highest current of 6:5 A lead to the shortest heatingtime for the MOF and thus to the highest space time yield of harvestedwater. At the same time the specific energy consumption was lowest atthis current. The subsequent experiments were carried out with a heatingcurrent of 6:5 A.

In the subsequent two experiments the influence of the fan, mountedbetween the fins of the heat sink, was investigated with the 110 Wpeltier device. As the change in the temperature in the MOF bed was veryhigh in the first experiment with the fan (WHC 4), two different flowrates of the fan were tested: A high flow rate with a fan current of0:09 A and a low flow rate with a fan current of 0:02 A. Besides, thetemperature to change to condensing current was set to 75° C. to enhancethe amount of desorbed water. The amount of harvested water in WHC 12with the low flow rate was 51:7 mL, the highest amount so far. As aresult, this experiment has the highest space time yield and lowestenergy consumption thus far with 0:833 L kg⁻¹ d⁻¹ and 3:06 kW h kg⁻¹,respectively. The amount of harvested water in WHC 13 with the high flowrate was just 36:7 mL, even though the fan was switched on after the MOFbed was heated up. In the previous experiment the fan was running thewhole time, including during the heating phase. Resultantly, thesubsequent experiments were carried out using the fan with a low flowrate. Furthermore, the fan was switched on when the MOF bed reaches thefinal desorption temperature, as the initial heating rate was 2:73° C.min⁻¹ compared to 2:13° C. min⁻¹ when the fan was switched on during theheating phase. The higher initial heating rate leads to shorterdesorption times and thus to shorter cycle times.

Based on these thirteen experiments, the 110 W peltier device was usedfor the further optimisation of the water harvesting device using thefollowing parameters for water harvesting cycle 14 to 24:

-   -   Peltier device MCTE1-12712L-2, 110 W.    -   Heating current 6:5 A.    -   Fan flow rate Low (I=0:02 A).    -   Fan run time Start after MOF bed heated up.        5.3.3 Optimisation of Operating Parameters

In the next experiments the condensation time; and desorptiontemperature were optimised. For this the condensation time was variedbetween 2 h and 5 min with a desorption temperature of 75° C. in WHC 14to 17, respectively. Subsequently the desorption temperature was variedbetween 75° C. and 45° C. with the best desorption time, determined inthe previous experiments, in WHC 18 to 20, respectively.

TABLE 5.3 Optimisation of the condensation time of the water harvestingdevice. Collected water over different condensation times. Condensationtime Water collected WHC (min) (mL) 12 120 51.7 14  90 42.8 15  60 37.216  30 26.3 17  5 11.2

Table 5.3 and FIG. 31 show the collected water, space time yield andspecific energy consumption of the device over different condensationtimes. As expected, the amount of water collected was greater for highercondensation times. However, the space time yield was better in a rangeof low condensation times with a maximum at 30 min. This was due to thesignificantly lower adsorption time that was necessary to adsorb theamount of water which was desorbed during the desorption phase. Only forvery short desorption times of 5 min, the space time yield was lower asthe time was not long enough to desorb a significant amount of waterfrom the MOF bed. The specific energy consumption also had a localminimum at a condensation time of 30 min. Thus the optimal condensationtime for the water harvesting device was determined to be 30 min. Basedon this condensation time the optimal desorption temperature wasdetermined in the subsequent experiments.

TABLE 5.4 Optimisation of the desorption temperature of the waterharvesting device. Collected water over different desorptiontemperatures. WHC Desorption Temp (° C.) Water collected (mL) 16 75 26.318 65 10.7 19 55 2.9 20 45 0.6

Table 5.4 and FIG. 32 show the collected water, space time yield andspecific energy consumption of the device over different desorptiontemperatures. All three parameters were greater with higher desorptiontemperatures. The most important factor was the specific energyconsumption as depicted in FIG. 32 . The energy consumption was greaterfor lower desorption temperatures as the energy was used to heat up theMOF and the heat sink but not for the desorption of water. Inconclusion, the best solution in terms of energy efficiency and spacetime yield was to heat the device to 75° C. before switching on the fanand condense for 30 min.

Water harvesting cycle 16 was the experiment with the highest space timeyield and the lowest specific energy consumption. The logged data ofthis cycle during adsorption and desorption is shown in FIGS. 33, 34 and35 .

The adsorption phase, shown in FIG. 33 , was under isothermal conditionswith a varying relative humidity between 50% and 70%. The averageloading of water in the air was 11:11 gm⁻³. The changes in relativehumidity were caused by the air conditioning system in the lab and theweather outside. The high temperature in the beginning was caused by thehot MOF bed and heat sink from the previous water harvesting cycle. Thedata logger was placed next to the heat sink, thus the air in thebeginning was hotter than the ambient air.

FIG. 34 shows the temperatures in the water harvesting device during thedesorption phase. The MOF bed was heated up to 75° C. before the fan wasswitched on after 33 min. The temperature in the MOF bed decreases afterthe fan was switched on, due to the higher convection in the container.After the first decrease, the temperature increases slowly and thecurrent of the peltier device was changed to 6:0 A after 53 min tomaintain a temperature of slightly above 70° C. The change in thecurrent was shown by the bend in the temperature curve of the MOF bedand the ΔT. The ΔT plot shows the temperature difference between the MOFbed and the condenser. This difference changes due to the higherconvection when the fan was switched on and due to the current changeafter 53 min. The air temperature in the container increased at nearly aconstant rate until the fan was switched on. The higher convection alsoresults in a higher air temperature as the heat was transported from theMOF bed into the air in the container.

FIG. 35 shows the temperature of the condenser as well as the relativehumidity and dew point in the container. The increase of relativehumidity was caused by desorption of water from the MOF bed. Therelative humidity decreases afterwards as liquid water condenses, andthe amount of new desorbing water decreases as well. The peak in therelative humidity graph might be a result of a droplet on the humiditymeter probe and was thus ignored in the discussion. This graph showsthat the condenser temperature was always lower than the dew point inthe system. Hence water vapour will condense on the condenser and can becollected afterwards. It was also observed that the walls of the deviceact as a second condenser, as a lot of droplets were forming on thewalls during the experiments.

With only the adsorption changed, the experiment was repeated under thesame conditions in WHC 24 to show the reproducibility of the results ofWHC 16. The adsorption phase was started with a desorbed and hot MOF bedfrom the previous experiment. The duration of the adsorption phase wasset to the length of the theoretical adsorption time used to calculatethe space time yield of WHC 16. Hence the adsorption time in WHC 24 was2:0 h and the desorption time was 1:06 h, resulting in a real cycle timeof 3:06 h.

FIG. 36 shows the adsorption phase of WHC 24. Compared to WHC 16 thewater loading in the air was lower with just 9:27 gm⁻³. 25:2 mL of waterwas collected after the desorption phase. This resulted in a space timeyield of 0:998 L kg⁻¹ d⁻¹. Compared to WHC 16 the space time yielddeviates by 2%. This demonstrates the reproducibility of the experimentswith high space time yields and confirms the calculation of thetheoretical adsorption time, used to calculate the space time yield inmost of the experiments.

As shown in FIGS. 37 and 38 the temperature graph of the MOF bed has agood match with the graph of WHC 16. The temperature after the fan wasswitched on was increasingly slower compared to WHC 16. Due to this thecurrent was not lowered in WHC 24 to maintain temperatures slightlyabove 70° C. Additionally, ΔT was higher in WHC 24 than in WHC 16. Thiswas due to the replacement of the heat grease between the heat sink andthe peltier device after WHC 20 affecting the thermal conductivitybetween the peltier device and the heat sink.

Furthermore, two water harvesting cycles, WHC 21 and 22, were run on thesame dry day (Aug. 3, 2019, Melbourne (AUS)) under very dry conditionsduring the adsorption phase. The relative humidity was between 25% and30% with a temperature of slightly about 20° C. The average waterloading in the air was 5:50 gm⁻³. FIG. 39 shows the adsorption phase ofWHC 22. The experiments of WHC 21 and WHC 22 showed that the lowrelative humidity leads to much longer adsorption times to adsorb thesame amount of water. As the adsorption time was constant, the amount ofwater adsorbed was lower compared to a higher relative humidity. As aconsequence the amount of harvested water in WHC 21 and 22 was lowerthan in the previous cycles, with a space time yield of 0:120 L kg⁻¹ d⁻¹and 0:274 L kg⁻¹ d⁻¹ for WHC 21 and 22, respectively. This was adeviation of 88% and 73%, respectively. Nevertheless, these resultsdemonstrate that the water harvesting device stills works in very dryand desert-like conditions.

Finally, FIG. 40 provides two views of a prototype water captureapparatus 800 that uses the temperature swing water harvesting apparatus300 shown in FIGS. 1C to 1E. FIG. 40(A) illustrates the external housing802 including the water dispensing outlet 805 activated by control panel808; and FIG. 40(B) illustrates the inner components, which essentiallyshow the fan 810 and louver system 820 for creating a flow ofatmospheric air into and over the water adsorbent, i.e. fan is operated,and pivots open the louvers of the louver system 820 allowing air toflow over and through the packed bed of MOF adsorbent (not shown in FIG.40 ) inside the apparatus packed into the heat sink (not shown in FIG.40 ), and when the fan is inactive, the louvers of the louver system 820pivot closed to create a closed environment, allowing the desorptionphase and condensation processes of the water harvesting cycle to takeplace in a closed/sealed environment.

Comparison Between Devices

Table 5.8 below provides a comparison between the water harvestingdevice as developed in this work in accordance with embodiments of thepresent invention and to Yaghi's MOF based water harvesting devices asdescribed in the background of the invention section. STY_(device) isthe space time yield with regard to the device's volume. X_(min)provides a measure of the environmental conditions, i.e. the humidity(minimum water content) of the air fed over the MOF adsorbent.

TABLE 5.8 Comparison between the water harvesting devices developed inthis work to other MOF based water harvesting devices. Energy STY massOutput consumption X_(min) device of Device (L/day) (kWh/L) (g m⁻³)(L/m³/d) MOF Yaghi Prototype* 0.078 sunlight 4.6 1.77 825 InventiveInduction 0.23 10.4 9.7 ~0.05 28 device (Example 1) Inventive Peltierdevice 0.202 2.75 9.3 4.59 ~200 (high RH) (Example 3) Inventive Peltierdevice 0.054 7.92 5.5 1.23 ~200 (low RH) (Example 3) *F. Fathieh, M. J.Kalmutzki, E. A. Kapustin, P. J. Waller, J. Yang, and O. M. Yaghi.“Practical water production from desert air”. In: Science Advances 4.6(2018).

The comparison indicate that both the tested embodiments of inductionand Peltier device water capture apparatus of the present invention havea better water output compared to the Yaghi devices.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is understood that the invention includes allsuch variations and modifications which fall within the spirit and scopeof the present invention.

Where the terms “comprise”, “comprises”, “comprised” or “comprising” areused in this specification (including the claims) they are to beinterpreted as specifying the presence of the stated features, integers,steps or components, but not precluding the presence of one or moreother feature, integer, step, component or group thereof.

The invention claimed is:
 1. A water adsorbent configured to capture awater content from air, the water adsorbent comprising: at least onewater adsorbent metal organic framework composite capable of adsorbing awater content from the air, wherein the at least one water adsorbentmetal organic framework composite comprises at least 70 wt % wateradsorbent metal organic framework and, wherein the water adsorbent metalorganic framework comprises: a metal ion selected from the groupconsisting of Fe³⁺, Li⁺, Na⁺, Ca²⁺, Zn²⁺, Zr⁴⁺, Al³⁺, K⁺, Mg²⁺, Ti⁴⁺,Cu²⁺, Mn²⁺ to Mn⁷⁺, Ag⁺, or combinations thereof; and at least 0.1 wt %of a hydrophilic binder selected from the group consisting of an alkylcellulose, a hydroxyalkyl cellulose, a carboxyalkyl cellulosederivative, or combinations thereof, and wherein the at least one wateradsorbent metal organic framework composite has an average surface areaof at least 700 m²/g and is configured to adsorb a water content fromthe air.
 2. The water adsorbent according to claim 1, wherein the atleast one metal organic framework composite comprises at least one ofpellets, pills, spheres, granules, extrudates, honeycombs, meshes,hollow bodies, or combinations thereof.
 3. The water adsorbent accordingto claim 1, wherein the hydrophilic binder is selected from at least oneof hydroxypropyl cellulose (HPC), hydroxypropyl cellulose, hydroxyethylmethyl cellulose, hydroxypropyl methyl cellulose (HPMC), ethylhydroxyethyl cellulose, methyl cellulose, or carboxymethyl cellulose(CMC).
 4. The water adsorbent according to claim 1, comprising between0.5 wt % and 3 wt % of the hydrophilic binder.
 5. The water adsorbentaccording to claim 1, comprising between 0.8 wt % and 2 wt % of thehydrophilic binder.
 6. The water adsorbent according to claim 1, whereinthe at least one water adsorbent metal organic framework compositecomprises at least one of a pellet, a coating, a plate, a sheet, or astrip.
 7. The water adsorbent of according to claim 1, wherein the atleast one water adsorbent metal organic framework composite comprises ashaped water adsorbent composite body comprising an elongate body havinga circular or regular polygonal cross-sectional shape.
 8. The wateradsorbent according to claim 1, wherein the at least one water adsorbentmetal organic framework comprises at least one of aluminium fumarate,MOF-801, MOF-841, CAU-10, MOF-303, MOF-573, MOF-802, MOF-805, MOF-806,MOF-808, MOF-812, or mixtures thereof.
 9. The water adsorbent accordingto claim 1, wherein the at least one water adsorbent metal organicframework composite has a particle size of less than 800 μm.
 10. Anapparatus for capturing a water content from air, the apparatuscomprising: a water adsorbent according to claim 1; and a waterdesorption arrangement in contact with and/or surrounding the wateradsorbent, the water desorption arrangement being selectively operablebetween (i) a deactivated state, and (ii) an activated state in whichthe arrangement is configured to apply heat, a reduced pressure or acombination thereof to the water adsorbent to desorb a water contentfrom the water adsorbent.
 11. The apparatus of claim 10, wherein the atleast one water adsorbent metal organic framework composite comprises acoating applied to the surface of the water desorption arrangement or isin thermal conductive contact with the water desorption arrangement. 12.The apparatus according to claim 10, wherein the water desorptionarrangement includes at least one heat transfer arrangement in directthermal conductive contact with the water adsorbent and the heattransfer arrangement is in thermal conductive contact with a heatingdevice.
 13. The apparatus according to claim 12, wherein the heattransfer arrangement includes at least one heat transfer element thatextends from the heating device to the water adsorbent.
 14. Theapparatus according to claim 12, further including a condenser systemfor cooling the product gas flow from the water adsorbent, wherein theheating device comprises at least one peltier device, and each peltierdevice has a hot side and a cold side, with the hot side of each peltierdevice being in thermal communication with the at least one heattransfer arrangement, and the cold side of each peltier device formingpart of the condenser system.
 15. The apparatus of claim 14, wherein thecold side of each peltier device is in thermal communication with atleast one heat transfer arrangement.
 16. The apparatus according toclaim 14, wherein the peltier device is capable of heating the packedbed to at least 50° C.
 17. The apparatus according to claim 12, whereinthe water adsorbent is housed within or coated on at least part of theheat transfer arrangement.
 18. A method of capturing a water contentfrom air, comprising at least one cycle of: feeding air over a wateradsorbent according to claim 1 such that the water adsorbent adsorbswater from the air; and applying heat, a reduced pressure or acombination thereof to the water adsorbent so to release at least aportion of the adsorbed water therefrom.
 19. The method according toclaim 18, wherein the water adsorbent is a shaped water adsorbent metalorganic framework having an average surface area of at least 700 m²/g.